Alhassanain(p) Network for Heritage and Islamic Thought

Lesson Fifty-Eight: Motion in Accidents

Introduction

The motion which is familiar to ordinary people is motion in space and position, such as the motions of the earth’s revolution about the sun and its rotation about its axis. However, philosophers have expanded the concept of motion to include any kind of gradual change, and they have established two other kinds of motion: one is qualitative motion, such as the gradual change of states and qualities of the soul, and the changes in color and shape of bodies. The other is quantitative motion, such as the gradual growth of a tree and the increase in its height. As a result, motion has been divided into four groups in accordance with the related category. All of these are related to accidental categories: motion in space, motion in position, qualitative motion and quantitative motion. The ancient philosophers did not allow motion in substance. There are only a few ancient Greek philosophers from whom some claims have been reported which are comparable to substantial motion. Among the Islamic philosophers, Ṣadr al-Muta’allihīn developed and gave numerous reasons in support of the existence of substantial motion. From this time, the problem of substantial motion became famous among Islamic philosophers. Here, we shall first review the four types of accidental motion, then we will discuss substantial motion independently.

Spatial Motion

As was indicated, the most sensible type of motion is spatial motion, whose channel is the space of bodies. Philosophers have introduced the category of where (’ayn ) as pertaining to its distance. However, as was previously mentioned, the category of where, like the other relative categories, is not a whatness of species or genus. Instead, it is a relational and relative concept, which is abstracted from the relation between a thing and its location. Space is also an analytic accident of bodies which does not have a entified object. In reality, the location of every thing is a part of the volume of the whole material universe which is considered separately, though it does not possess a separate existence.

Anyway, motion in space is either intentional, as when a man transfers himself from one place to another of his own will, or non-intentional, like the spatial movements of non-living bodies. Non-intentional motion, in turn, is divided into natural and unnatural motion, for it is either required by the nature of the thing, or it is under the influence of a constraining force.

Intentional motion, which is based on the soul of the willing agent, is really a subordinative (taskhīrī ) action which would not occur without the intermediary of the soul. The souls of animals and men use a natural agent to move their bodies or other objects, so the direct and proximate agent of intentional motion is nature.

On the other hand, constrained motion, whether it derives from that which constrains (qāsir ), as asserted by us, or from that which is constrained ( maqsūr ), as most philosophers have held, is ultimately produced by the nature of the body. Hence, every motion derives from nature, and for this reason, nature is introduced as the agent source ( mabda’ fā’ilī ) of the motion of bodies. In other words, every motion has a source of its tendency

( mabda’ maylī ) which is either a property of the body’s nature or appears by means of the influence of the nature of another thing.

The ancient philosophers presented views about the source of motion in moving bodies, some of which were discussed in Lesson Thirty-Eight. However, their explanations were based on the assumptions of the then current natural sciences and do not correspond to contemporary scientific theories. But, in general, it can be said that corporeal motion does not lie beyond these two alternatives: either it is required by the nature of the moving existent—and in this case the motion continues until it confronts an obstacle—or the essence of the moving existent does not require motion, but it occurs under the influence of a foreign factor. If this foreign factor itself does not require motion essentially, another factor will have to exist, until it culminates in a material factor that essentially requires motion. This factor corresponds to the thing which in modern physics is called ‘energy.’ It is the transference of energy to bodies which causes their motion. But it must be noted that the validity of this correspondence depends on the validity of the related scientific theory. However, the existence of a natural factor that essentially requires motion is a philosophical theory to which the correctness or incorrectness of scientific theories makes no difference.

Motion in Position

Just about everything that has been said about spatial motion applies to motion in position as well. Basically, motion in position may be reduced to spatial motion because although in motion in position the place of the entire body does not change, the parts of the moving thing gradually change location, so that, for example, the part which was to the right moves to the left, or the part which was above moves below.

The discussion of whether position is really a category is similar to that about the category of where (’ayn ). The division of motion in position into intentional and the non-intentional is similar to the corresponding division in spatial motion.

A notable point is that philosophers do not consider circular motion to be required by nature, and in this regard modern physics says that motion which is not in a straight line must be the resultant of several forces. The final judgment about this kind of problem is the responsibility of the empirical sciences.

Motion in Quality

The third category in which motion occurs is the category of quality. It may be further subdivided by attending to its kinds, such as motion in mental quality, motion in sensible quality, motion in qualities specific to quantity and motion in dispositional qualities (kayf isti‘dādī ).

The most indubitable among the types of motion in quality, is motion in mental quality, for it is perceived by infallible presentational knowledge. For example, everyone finds within themselves an affection or love for someone or something, and gradually this attraction becomes intense. Or one feels a dislike toward someone or something which gradually changes into an intense loathing, or the opposite, a state of intense anger appears and gradually is mollified, or a state of intense joy appears and gradually

vanishes. From a philosophical point of view, these gradual changes are considered motion.

Motions such as these may be considered to be like sensible qualities, such as color, but we know that the reality of color and the qualities of their intensity and weakness are still subjects of discussion among physicists. Therefore, the existence of this type of motion in quality is not as certain as the previous type.

The third type of motion in quality is motion in shape. If two ends of a string which are extended to form a straight are line gradually brought together in such a way that a curve is formed, then the plane surface and its straight line (if the line it possesses is actual) gradually becomes curved. However, if this transformation is really gradual, it will be subordinate to motion in the position of the string itself or to the spatial motion of its parts.

Another example of this kind of motion in quality may be found in the speeding up or slowing down of any motion, because it is a quality specific to the quantity of its speed, as was explained in the previous lesson.

The fourth kind of motion in quality is motion in dispositional qualities and their gradual intensification and weakening. However, in Lesson Forty-Eight it became clear that the concept of disposition is a kind of concept which is abstracted from the decrease and increase in the conditions for the occurrence of a phenomenon. Therefore, if the occurrence of the conditions is really gradual, the motion in the disposition of quality can be considered a concept abstracted from several motions. If it is assumed that the occurrence of a phenomenon depends on only one condition, and that this condition really comes about gradually, then in this case, motion in dispositional quality can be considered a concept abstracted from the motion of the mentioned condition.

Motion in Quantity

Motion in the category of quantity for a moving body is assumed either in disjoint quantity and number, or in continuous quantities and amount. But in addition to the fact that number does not have real existence, it makes no sense to speak of numbers changing gradually, for change in number is obtained only by means of increase or decrease in units, and these increases and decreases occur instantaneously, although it may be based on gradually fulfilled prerequisites or spatial motion.

If motion in continuous quantity is supposed in a line, its changes depend on the changes in the surface [on which the line exists], and the changes in a surface in turn depend on the changes in volume, and until the volume of something increases or decreases the amount of its surface or lines will not increase or decrease.

An increase in volume will be obtained either as an effect of the attachment of another body or as an effect of the expansion and extension of its own parts. Likewise, a decrease in the volume of a body will occur either as an effect of the removal of a section from it, or as an effect of pressure on its existing parts. Change which is obtained as a result of composition and decomposition, attachment and detachment, is usually instantaneous, although the prerequisites for it might be fulfilled gradually. However, a case of gradual composition and decomposition may be imagined, for

example, such that two liquids each of which is assumed to possess a true individual unity are gradually poured into one another so that they are mixed and a third liquid with its own individual unity results. Regarding the fact that every compound liquid is composed of uncountable molecules, the proof of individual unity for each of the two assumed liquids and for the mixture of the two is exceedingly difficult. In reality, this kind of analysis and synthesis are sets of instantaneous connections and disconnections which appear following the spatial motion of the parts.

Decrease or increase in the volume of a body as a result of the expansion or compression of its parts are in fact another way of describing motion in space and position of its molecules and atoms. For example, when water boils and turns into steam its volume increases, but this increase in volume, according to that established by physicists, is nothing but the increase in the distance of the molecules of water. Likewise the transformation of steam into water and gas into liquid is nothing but the decrease in the distance of these molecules and atoms.

Therefore, the growth of plants and animals has been considered a clear instance of motion in quantity, and although it is obtained by addition of other bodies such as water and nutrients, it is assumed that each of them possesses a single specific form whose amount gradually increases.

It seems that the establishment of true motion in quantity is also difficult in these cases because undoubtedly vegetable growth is under the influence of the addition of foreign materials which are transferred into them by spatial motion, and the connections and disconnections of their parts take place instantaneously. Likewise, when two bodies move toward each other, or one of them moves toward the other, although they gradually approach each other, their attachment takes place at a single instant and without any duration. After their new parts are put in their places, although their chemical and physiological actions and reactions take place gradually, there is no reason that the specific form of a tree or an animal also develop gradually to include the new part. It is possible that the change of the prior quantity to the new quantity occurs instantaneously, and is a kind of generation or corruption, not something gradual and a kind of motion in quantity.

It is to be concluded that demonstrating that there is motion in quantity is more difficult than demonstrating the other kinds of motion. It is possible that what is called motion in quantity is really a set of spatial motions, instantaneous connections and disconnections, or instantaneous generation and corruption.

Lesson Fifty-Nine: Motion in Substance

Introduction

As was indicated, philosophers of the past, including Aristotelians and Illuminationists, considered motion to be specific to accidents. Not only did they fail to establish substantial motion, but they imagined it to be impossible. Also, among the ancient Greek philosophers none are to be found who explicitly discuss substantial motion or establish it. The only position which is comparable to substantial motion is that reported to have been held by Heraclitus (540-470 B.C.). Other than those Islamic and non-Islamic philosophers and theologians who believed in constant renewing creation, none are found to whom a tendency toward substantial motion can be ascribed. However, contrary to the famous philosophers of the world, the one who explicitly established substantial motion and boldly insisted on it was the great Islamic philosopher, Ṣadr al-Muta’allihīn Shīrāzī.

Here, we shall first present the objections raised by those who deny substantial motion and answer them, then we shall explain the theory of Ṣadr al-Muta’allihīn and the arguments he has put forth to prove it.

Objections to Substantial Motion

The discussions of those who imagine substantial motion to be impossible turn on the notion that one of the prerequisites, or rather one of the constituents, of every motion, is the existence of the moved, or in technical terms, the subject of motion. When we say that the earth rotates on its axis and revolves around the sun, or that an apple turns from green to yellow and then to red, or that a sapling or a baby animal or human grows and develops, in each of these cases we have a fixed essence whose attributes and states gradually change. However, if it is said that the essence itself is not fixed, and just as its attributes and accidents change, its substance also is transformed, then to what are we to relate this change? In other words, substantial motion will be a motion without a thing moved and an attribute without a thing to which attribution is made. This is not rational.

Answers to the Objections

The origin of this objection is a defect in the analysis of motion. As a result, some philosophers, such as al-Shaykh al-Ishrāq, have consciously considered motion to belong to the category of extraneous accidents, while others have unconsciously considered it so. Hence, they considered it necessary for there to be a entified independent subject of motion and attribution which remains fixed through the process of motion, and to which motion and change are related as accidents and attributes.

However, as was previously made clear, motion is that very flowing of the existence of substances and accidents, not an accident alongside other accidents. In other words, the concept of motion is not a whatish concept, rather it is a secondary philosophical intelligible. To put it still differently, motion is an analytic accident of existence, not an extraneous accident of existents. These sorts of concepts do not need a subject in the sense which has been established for accidents. The only thing that can be considered as the source of abstraction of motion is the flowing substantial or accidental

existence itself, in the sense of a subject related to analytic accidents, that is, a subject whose objective existence is identical with an accident, and any distinction between them is impossible except in the realm of mental analysis.

Therefore, when we say, ‘A substance has changed,’ it is as if we were to say, ‘the color of the apple (and not the apple itself) has changed.’ It is clear that in the process of a transformation in color, there is no fixed color to which the transformation is attributed. Even an independent subject is related to accidental motions only because of its being an accident, not because it is motion. Therefore, even if the accident pertaining to the motion were to remain unchanged, it would still need a subject, as the apple itself is needed whether its color is fixed or changing.

It is to be concluded that motion and immutability are two analytic attributions for flowing and immutable existence, and such attributions do not require entified subjects of attribution independent of the attribution itself. In the same way as immutability is not an accident of an existent in external reality in such a way that it would lack immutability without that accident, likewise, the attribute of motion is not is not an extraneous accident of a particular existent so that without it, it should be characterized with immutability and lack of motion. In technical terms, analytic accidents do not require independent subjects; rather their existence is identical with the existence of their subjects.

It is worth noting the subtle point that according to the fundamentality of existence, motion must be related to existence as an analytic accident, and the relating of it to the whatness of a substance or accident is an accidental relation.

Arguments for the Existence of Substantial Motion

Ṣadr al-Muta’allihīn offered three lines of argument to establish substantial motion.

1. The first argument for substantial motion has two premises. One is that accidental changes in a thing are the effects of the substantial nature of that thing. The second premise is that the natural cause of motion must be a moving thing. From this it is concluded that a substance which is the cause of motion in accidents must be a moving thing.

As for the first premise, this is the famous principle indicated in the previous lesson, that is, the proximate and immediate agent of all motions is nature, and no motion can be directly related to an immaterial agent.

As for the second premise, it may be further explained that if the proximate and immediate cause of an effect were a stationary object, its result would also be a stationary. In order to make this easier to understand, the following example may be used: if a lamp were in a fixed place the light which radiates from it would illuminate all within a specific radius, but if the lamp were in motion, the extent of its illumination would gradually advance. Hence, the process of moving accidents which advance in the realm of time shows that their cause also is in process along with them.

Perhaps it will be asked, if the nature of a substance is essentially in motion, then why are its effects, which are accidents, sometimes without

motion? And why cannot the immobility of accidents be reason for the immobility of the nature of a substance?

These question can be answered as follows. The nature of a substance is not a complete cause of motion, rather, its effectiveness depends on specific conditions whose satisfaction brings about motions in accidents, and motion is an action which requires a natural agent, even if the agent is not the complete cause of its occurrence. Immobility, to the contrary, is a negative thing (the absence of motion), and cannot be considered to be an action in need of an agent.

On the other hand, it may be asked whether the proponents of substantial motion are not forced to relate substantial motion to immaterial agents, which are fixed, unchangeable and devoid of motion. Why do they not accept accidental motion for fixed substances as valid?

The answer is that substantial motion is the very existence of the substance, and is merely in need of a divine generative agent, and the granting of existence to the substance is the same as the granting of existence to the substantial motion. However, the granting of existence to the substance is not the same as the granting of existence to accidents and to motion in accidents. For this reason, the motion in accidents is related to substantial nature, and is considered an action for it. Such an action is in need of a natural agent whose transformation shows a transformation in its agent.

Another very precise objection can also be raised against this argument, the answer to which is not as easy as the answer to the previous two objections. According to Ṣadr al-Muta’allihīn’s own explanation, motion is not a entified object independent of its source of abstraction, the flowing existence of a substance or accident. Hence, whether it is assumed to be in a substance or in an accident, motion will be the same as the existence of that substance or accident, and its cause will be the cause of the existence of that substance or accident. Therefore, what prevents us from relating the flowing existence of an accident directly to a divine or metaphysical agent and to consider the role of substance in its occurrence as the role of matter for the occurrence of form rather than as the efficient cause (‘illat fā‘ilī )? If this assumption is correct, there will be no way to infer substantial motion from the agency of substance for its accidents and their motions. In fact, this objection arises from doubts about the first premise. But, in any case, this argument at most will be of benefit to those who consider the agency of substantial nature for their accidents and motions to be debatable.

2. The second argument also has two premises. One is that accidents do not have existence independent of their subjects, but rather they are really aspects of the existence of substance. The second premise is that every kind of change that occurs in an aspect of an existent, is a change in the existent itself, and indicates its own internal and essential change. It is concluded that motions in accidents indicate changes in the existence of a substance.

In explaining this argument, Ṣadr al-Muta’allihīn says that every corporeal existent has a single existence which is in itself determinate and individual (as was explained in Lesson Twenty-Five). The accidents of every substance are appearances or rays of its existence, which may be

considered signs of individuation (‘alāmāt tashakhkhuṣ ) for it and not as causes of its individuation. Therefore, a change in these signs indicates a change in that which bears the sign; hence, motion in accidents indicates motion in the existence of a substance.

This argument does not depend on the assumption that motion in accidents is an effect of substantial nature, but rather accidents are introduced as appearances and aspects of the existence of a substance. This position is acceptable in the case of continuous quantities because the dimensions and extensions of corporeal existents are nothing but their visages, as was explained in Lesson Forty-Seven. It can also be applied in the case of qualities specific to quantity, such as geometrical shapes. However, relative categories, as was mentioned repeatedly, are abstract concepts and only the source of abstraction of some of them, such as time and space, can be considered to be aspects of the existence of substance, which reduce to continuous quantities. The existence of psychic (nafsānī ) qualities (which in a precise sense are objective accidents, although in a sense they may be considered to be appearances and aspects of the psyche) is not the same as the existence of the psyche. Rather, there is a sort of union (not unity) between these qualities and the psyche, and for this reason, the application of this argument for such accidents is difficult.

3. The third argument given by Ṣadr al-Muta’allihīn for substantial motion is obtained from knowledge of the reality of time as a flowing and passing dimension of material existents, and the logical form of this argument is as follows.

All material existents are in time and have a temporal dimension. Every existent which has a temporal dimension has gradual existence. In conclusion, the existence of a material substance will be gradual, that is, possessing motion.

The first premise was made clear in Forty-Three, from which it may be concluded that time is the passing extension of corporeal existence, not an independent vessel in which they are contained. If material phenomena did not have such a passing extension, they could not be measured with temporal scales, such as clocks, days, months and years. Likewise, if they did not have spatial extensions and geometrical dimensions, they could not be measured by length, area and volume. Basically, the measurement of everything by a specific scale shows the homogeneity between them. Therefore, the weight of something can never be measured by the scale of length or vice versa. It is for this reason that completely immaterial things do not have a temporal duration, and they cannot be considered temporally prior to or posterior to an event, for their immutable existences are not homogeneous with the passing and renewing extension of time.

The second premise can be explained as follows. Time is passing so that its potential parts are brought about successively. One part of it does not occur until another part passes, while the entirety of its supposed parts have a single existence. It we understand the nature (ḥaqīqat ) of time, we will readily discover that every existent which possesses this sort of extension in its essence will have a gradual existence and will have parts spread out in the channel of time. Its temporal extension is divisible into successive

potential parts no two of which can be brought together. Until one of them passes and is annihilated another part will not be brought into existence.

Given these two premises, it can be concluded that the existence of a corporeal substance is gradual, passing, and constantly renewed, and this is the meaning of substantial motion.

In explaining this argument, Ṣadr al-Muta’allihīn says that just as a material substance has geometrical and spatial dimensions, it also has another continuous quantity called time (which constitutes its fourth dimension), and just as its instantaneous extension is an essential attribute of its existence, and has no existence separate from that of the material substance, likewise its gradual extension is an inseparable and essential attribute for it. And just as the individual ipseity of a corporeal substance is never brought about without geometrical dimensions, likewise it cannot occur without the temporal dimension. No corporeal substance can be imagined to be fixed and detached from time, and therefore as related equally to all times. So, time is a constituent of the existence of every corporeal substance. This implies that the existence of every corporeal substance is gradual and that its supposed parts are brought into existence successively and by constant renewal. This argument is the firmest of the arguments for substantial motion, and there appear to be no problems with it.

Lesson Sixty: Further Discussion of Substantial Motion

A Reminder of Some Points

An important problem regarding substantial motion has been raised which will be reviewed at the end of this section, but prior to this, there are several points which should be borne in mind.

1. Substantial motion is really the instant to instant renewal of the existence of a substance, and bears no relation to the motion of the stars, galaxies and nebula, nor to the motions of atoms and molecules or the motion of particles around the nuclei of atoms. Even if motion within the nucleus is assumed, this will have no relation to substantial motion, because these motions are spatial and accidental, while substantial motion is basically a philosophical and intellectual notion and not a scientific or empirical one.

2. Accidents which appear to be stationary and motionless have constant imperceptible motion, for their existences are also extended in the channel of time, and until one of their temporal parts is annihilated, another part will not appear. Therefore, all the material world is continuously being annihilated and renewed. No stationary and immobile existent is to be found. In other words, the existence of immobility is relative and absolute immobility does not exist.

3. It is possible for a material existent to possess numerous motions at a single time, as the planet earth, like all material substances, has substantial motion, and on that basis, its existence is constantly being renewed and likewise all its attributes and accidents are continuously being renewed in existence. Furthermore, it rotates on its axis while it revolves around the sun, and it also has other motions which have been established by astrophysicists.

Likewise, it is possible for a body subordinate to another moving body to possess one or more subordinate motions. For example, as the existents on the earth are subordinate to it, they possess motion subordinate to it, even if they do not move independently, just as the earth itself has a motion subordinate to that of the solar system in the galaxy, it also has a motion in space subordinate to that of the galaxy. Therefore, the unity of a moving thing is no reason for the unity of motion, although the individual unity of motion would be meaningless without the unity of the moving object.

4. Sometimes, numerous motions are directly attributed to a moving object, but sometimes, motion occurs in a moving object by means of another motion, without which it could not occur, as in the serpentine motion of the earth which is obtained by means of its revolutions, which is in fact an attribute of this motion, or the motion of an automobile which is attributed to the gradual increase or decrease of its speed (acceleration), or the substantial motion of bodies, which are attributed with intensity and perfection. These sorts of motions are calledmotions superimposed on motions .

5. As was previously said, the concept of speed is obtained through the relation between time and distance. Hence, speed is not attributed to time

itself, and naturally, acceleration or the increase and decrease in speed will also have no meaning for time. Therefore, when it is said that time has passed quickly or slowly, this is called ‘psychological time’ and is a loose way of speaking, and it depends on the quality of the perception of the passage of time. Such ideas may also be applied to physical time.

Types of Substantial Motion

Substantial motion, like other kinds of motion does not by itself necessitate perfection and intensity, and the arguments for its existence do not prove anything more than gradual change and renewal of the existence of a substance. Therefore, as in the case of accidental motion, three states may be posited for it, or it may be divided into three types:

1. Constant motion in which all the potential parts of the substance are equal with respect to perfection and level of existence.

2. Intensifying motion in which every assumed part is more perfect than the previous part.

3. Weakening or declining motion in which every part is weaker and more defective than its predecessor.

Intensifying and weakening motions can be considered to be composed of two motions: (1) one which occurs to the moving thing by means of another; (2) motion without an intermediary, which represents the persistence of a substance, whereas the mediated motion represents its perfection or decline. It is like accelerating motion, whose increase or decrease in speed is considered an ascending or declining motion over spatial or another kind of motion. A motion that begins with positive acceleration and then has negative acceleration can be represented in the form of a straight line over which from the beginning a curve rises and then falls back to meet the straight line at its end point. The ascending curve represents positive acceleration, and the descending curve represents negative acceleration.

This picture has a clearer instance in the case of substances which possess two compound forms, in such a way that the underlying form possesses a constant substantial motion, whose level of existence does not become more perfect nor decline, while the higher form possesses rising and declining motion. For example, the component elements of a plant remain in the same condition in which they began, while the vegetable form gradually becomes more perfect, and then enters the state of withering and decaying, and at last it rots and is destroyed. This is the point at which the descending curve joins the straight line.

Those who rely on some other definitions of motion have inferred the necessity of its becoming perfect, and so, in the case of substantial motion, they have also held that its intensification and becoming more perfect are necessary, even if our senses are not able to perceive this intensification. In the same way, they have considered declining or weakening motions to be accidental. In Lesson Fifty-Seven, this inference was criticized and its weakness was made clear. There is no reason to repeat it again.

The Relation between Substantial Motion and Actuality and Potentiality

As was previously explained, the potential and the actual are two abstract concepts abstracted from the relation between two successive existents, and from the persistence of the previous existent or a part of it in the following existent. Now, regarding the fact that all material existents are constantly in a state of renewal and coming about and passing away, the question will be raised as to how the existence of the previous existent can be imagined, and how the definition of potential and actual can apply to the beginning and end of the motion.

Sometimes the answer is given that although the previous existent does not itself remain, the perfection of its existence is preserved in the following existent. It is concluded that every motion is a becoming perfect and intensification. However, not only does this conclusion fail to agree with entified reality, but the answer itself does not solve the basic problem, for given the annihilation of the previous existent, the preservation of its perfections can mean only that the succeeding existent is more perfect than the previous one, and this reduces to the fact that the preservation of something from a potential existent in an actual existent is not necessary. This meaning is compatible with the assumption of the succession of numerous existents each of which is more perfect than the other, and with the interpretation of motion as a succession of actualities which is governed by the principle of ‘a succession of rests.’

It might be said that according to the position of the constancy of motion, the earlier and later parts are not numerically different in actuality, but all of them are an existent with a single existence. This is contrary to the position of a succession of rests, according to which each of the temporal parts will have a specific actual existence. According to the former position, a single flowing existence is infinitely analyzable, contrary to the latter position which is based on finite unanalyzable parts.

However, the discussion is not about the potential parts of motion, but about the potential and actual as the beginnings and ends of motion which are outside the scope of the motion itself. This may be explained further by pointing out that motion has been defined as the gradual process of the emergence of the actual from the potential, such that the potential is the beginning of the motion and the actual is its end. However, to call the earlier part of motion potential in relation to a later part is to use a specialized expression, according to which the perseverance of something from the earlier part is not considered necessary, and in this way there no longer remains room for a gradual process from potentiality to actuality and a temporal gap between them.

It seems that the application of the above definition to substantial motion is extremely difficult. It is only in the case of the compound forms whose underlying form is a previous existent that it can be considered potential in relation to the occurrence of the higher form, which is the substantial motion itself, although this higher form is the very motion, for the perseverance of a part of its motion is sufficient during the occurrence of the higher form. However, in the case of simple and constant substantial motion the potential and actual cannot be proven to be two existents outside the scope of motion as its beginning and end.

If we assume that there is nothing but a simple body in the world, and throughout time it remains with the same constant level of existence, and that its potential parts continuously come into existence and are annihilated, is it necessary for there to exist an existent prior to or after it as its beginning or end?

Therefore, it becomes clear why it is preferable to define motion generally as ‘gradual change’ rather than in the other ways proposed.

The Continuity of Substantial Motion

In Lesson Twenty-Nine, the unity of the world was discussed, and different meanings which have been assumed for it were reviewed. However, the establishment of unity in none of the mentioned senses depended on the establishment of substantial motion. Sometimes, substantial motion is used as a justification to establish the unity of the material world, and the unity of the world is even considered to be one of the conclusions of the doctrine of substantial motion. It is said that with the establishment of substantial motion, the entire material world will be a single substantial motion, from each of whose slices a specific whatness is abstracted, and the multiplicity of material existents depends upon the numerical differences among these essences.

This subject may be interpreted to mean that the accidents and motions of a material existent are aspects and representations of the existence of a substance. In fact, their existences are derived from the existence of the substance. The material substances themselves are in fact continuous substantial motions which can be considered a single existent given their attachment to each other. On this basis it may be claimed that the entire material cosmos is a single continuous existent.

The continuity of substantial motions may be interpreted in two ways: one is the continuity of motions which are brought about successively during time, which may be called vertical continuity; and the other is the continuity of simultaneous motions which occur along with each other, which may be called horizontal continuity. Therefore, each of the two forms will be discussed separately.

Vertical Continuity

Regarding the vertical continuity of material existents and their substantial motions, it can be said that every particular material existent which may be considered is a particular substantial motion which appears in matter. For example, the existence of a plant is a substantial motion which occurs in its component elements. But its prior matter also has a substantial motion in its own turn. Likewise, however far we go back we always reach another substantial motion, and among them there is never any gap brought about by rest. Therefore, it can be said that successive phenomena are a single substantial motion possessing numerous slices, from each of which specific whatnesses are abstracted.

This explanation is debatable in two respects. First, it is not the case that each of the particular slices possess a single existence and a single substantial motion; rather it is possible that a compound existent may be

compound in several ways and possess several substantial motions, as was established in Lesson Fifty-Four.

Second, the continuity of two successive substantial motions will have unity in a real sense when there is no distinctive boundary between them, while the transformation of one material existent to another is not like this. The reason for this is that there are various effects for each of them. For example, vegetative effects, that is, growth and reproduction, are new effects which appear in matter, and there is no precedent for this in lifeless matter, and it begins when the vegetable form occurs in matter. Even if the vegetable form is the same as the vegetable substantial motion, it possesses a determinate boundary which separates it from the substantial motion of the previous matter. In other words, in the extension of the substantial motion of matter there are points which are boundaries between mineral and vegetable, and from these points new substantial motions appear which can be shown by a curved line which meets the underlying straight line at two points. Therefore, successive substantial motions are continuous linear fragments which are distinguished from one another by specific points, each of which linear fragments possesses its own characteristics.

Since these points are drawn by means of the higher lines, the underlying straight line which continues through time can be considered a single line which shows the continuous unity of the prime matter of the cosmos through time. And it is only in this sense that the unity of the material cosmos can be established.

Horizontal Continuity

Regarding the horizontal continuity of material existents and their substantial motion, it may be said that since nothingness has not made any gaps between the parts of matter, and there is no pure vacuum between them, all of them possess a unity of continuity, and this unified thing possesses a single substantial motion.

Aside from the fact that in the above explanation the continuity of substantial motion is inferred from the unity of matter, not that the unity of the cosmos is established through the unity of substantial motion, there is another problem with this view, that is, the unity of continuity for the matter of the cosmos is no reason for the unity of its forms and the unity of their substantial motions, for it is obvious that each of the forms possesses a distinctive boundary and particular effects which have no relation to the effects of the common matter. Therefore, the correctness of the doctrine of the horizontal continuity of material existents and their substantial motion is merely due to the unity and continuity of their matter. This sort of unity and continuity is not incompatible with the multiplicity of forms and their generation and corruption.

Part VII: Theology