(23) The Motion which acts upon Sensible objects enters from without, and so shakes, drives, rouses and thrusts its participants that they may neither rest nor preserve their identity- and all to the end that they may be caught into that restlessness, that flustering excitability which is but an image of Life.

We must avoid identifying Motion with the objects moved: by walking we do not mean the feet but the activity springing from a potentiality in the feet. Since the potentiality is invisible, we see of necessity only the active feet- that is to say, not feet simply, as would be the case if they were at rest, but something besides feet, something invisible but indirectly seen as an accompaniment by the fact that we observe the feet to be in ever-changing positions and no longer at rest. We infer alteration, on the other hand, from the qualitative change in the thing altered.

Where, then, does Motion reside, when there is one thing that moves and another that passes from an inherent potentiality to actuality? In the mover? How then will the moved, the patient, participate in the motion? In the moved? Then why does not Motion remain in it, once having come? It would seem that Motion must neither be separated from the active principle nor allowed to reside in it; it must proceed from agent to patient without so inhering in the latter as to be severed from the former, passing from one to the other like a breath of wind.

Now, when the potentiality of Motion consists in an ability to walk, it may be imagined as thrusting a man forward and causing him to be continually adopting a different position; when it lies in the capacity to heat, it heats; when the potentiality takes hold of Matter and builds up the organism, we have growth; and when another potentiality demolishes the structure, the result is decay, that which has the potentiality of demolition experiencing the decay. Where the birth-giving principle is active, we find birth; where it is impotent and the power to destroy prevails, destruction takes place- not the destruction of what already exists, but that which intervenes upon the road to existence.

Health comes about in the same way- when the power which produces health is active and predominant; sickness is the result of the opposite power working in the opposite direction.

Thus, Motion is conditioned, not only by the objects in which it occurs, but also by its origins and its course, and it is a distinctive mark of Motion to be always qualified and to take its quality from the moved.

(8) Of this I'll give thee here on earth an instance, which the eye can see. Regard the animals down here - a man, for instance, swimming! The water moves, yet the resistance of his hands and feet give him stability, so that he is not borne along with it, nor sunk thereby. A: Thou hast, Thrice-greatest one, adduced a most clear instance. H: All motion, then, is caused in station and by station. The motion, therefore, of the cosmos (and of every other hylic to the cosmos, but by things interior [outward] to the exterior - such [things] as soul, or spirit, or some such other thing incorporeal. 'Tis not the body that doth move the living thing in it; nay, not even the whole [body of the universe a lesser] body e'en though there be no life in it.

(3) The truth may be resumed in this way:

There is a lowest power of the Soul, a nearest to earth, and this is interwoven throughout the entire universe: another phase possesses sensation, while yet another includes the Reason which is concerned with the objects of sensation: this higher phase holds itself to the spheres, poised towards the Above but hovering over the lesser Soul and giving forth to it an effluence which makes it more intensely vital.

The lower Soul is moved by the higher which, besides encircling and supporting it, actually resides in whatsoever part of it has thrust upwards and attained the spheres. The lower then, ringed round by the higher and answering its call, turns and tends towards it; and this upward tension communicates motion to the material frame in which it is involved: for if a single point in a spheric mass is in any degree moved, without being drawn away from the rest, it moves the whole, and the sphere is set in motion. Something of the same kind happens in the case of our bodies: the unspatial movement of the Soul- in happiness, for instance, or at the idea of some pleasant event- sets up a spatial movement in the body: the Soul, attaining in its own region some good which increases its sense of life, moves towards what pleases it; and so, by force of the union established in the order of nature, it moves the body, in the body's region, that is in space.

As for that phase of the Soul in which sensation is vested, it, too, takes its good from the Supreme above itself and moves, rejoicingly, in quest of it: and since the object of its desire is everywhere, it too ranges always through the entire scope of the universe.

The Intellectual-Principle has no such progress in any region; its movement is a stationary act, for it turns upon itself.

And this is why the All, circling as it does, is at the same time at rest.

(4) And if all things in motion desire, not repose, but ever to make known their own proper movement, even this is an aspiration after the Divine Peace of the whole, which preserves all things from falling away of their own accord, and guards the idiosyncrasy and moving life of all moving things unmoved and free from falling, so that the things moved, being at peace amongst themselves, and always in the same condition, perform their own proper functions.

(24) With regard to locomotion: if ascending is to be held contrary to descending, and circular motion different from motion in a straight line, we may ask how this difference is to be defined- the difference, for example, between throwing over the head and under the feet.

The driving power is one- though indeed it might be maintained that the upward drive is different from the downward, and the downward passage of a different character from the upward, especially if it be a natural motion, in which case the up-motion constitutes lightness, the down-motion heaviness.

But in all these motions alike there is the common tendency to seek an appointed place, and in this tendency we seem to have the differentia which separates locomotion from the other species.

As for motion in a circle and motion in a straight line, if the former is in practice indistinguishable from the latter, how can we regard them as different? The only difference lies in the shape of the course, unless the view be taken that circular motion is "impure," as not being entirely a motion, not involving a complete surrender of identity.

However, it appears in general that locomotion is a definite unity, taking its differences from externals.

(22) But suppose that we identify alteration with Motion on the ground that Motion itself results in difference: how then do we proceed to define Motion?

It may roughly be characterized as the passage from the potentiality to its realization. That is potential which can either pass into a Form- for example, the potential statue- or else pass into actuality- such as the ability to walk: whenever progress is made towards the statue, this progress is Motion; and when the ability to walk is actualized in walking, this walking is itself Motion: dancing is, similarly, the motion produced by the potential dancer taking his steps.

In the one type of Motion a new Form comes into existence created by the motion; the other constitutes, as it were, the pure Form of the potentiality, and leaves nothing behind it when once the motion has ceased. Accordingly, the view would not be unreasonable which, taking some Forms to be active, others inactive, regarded Motion as a dynamic Form in opposition to the other Forms which are static, and further as the cause of whatever new Form ensues upon it. To proceed to identify this bodily motion with life would however be unwarrantable; it must be considered as identical only in name with the motions of Intellect and Soul.

That Motion is a genus we may be all the more confident in virtue of the difficulty- the impossibility even- of confining it within a definition.

But how can it be a Form in cases where the motion leads to deterioration, or is purely passive? Motion, we may suggest, is like the heat of the sun causing some things to grow and withering others. In so far as Motion is a common property, it is identical in both conditions; its apparent difference is due to the objects moved.

Is, then, becoming ill identical with becoming well? As motions they are identical. In what respect, then, do they differ? In their substrates? or is there some other criterion?

This question may however be postponed until we come to consider alteration: at present we have to discover what is the constant element in every motion, for only on this basis can we establish the claim of Motion to be a genus.

Perhaps the one term covers many meanings; its claim to generic status would then correspond to that of Being.

As a solution of the problem we may suggest that motions conducing to the natural state or functioning in natural conditions should perhaps, as we have already asserted, be regarded as being in a sense Forms, while those whose direction is contrary to nature must be supposed to be assimilated to the results towards which they lead.

But what is the constant element in alteration, in growth and birth and their opposites, in local change? What is that which makes them all motions? Surely it is the fact that in every case the object is never in the same state before and after the motion, that it cannot remain still and in complete inactivity but, so long as the motion is present, is continually urged to take a new condition, never acquiescing in Identity but always courting Difference; deprived of Difference, Motion perishes.

Thus, Difference may be predicated of Motion, not merely in the sense that it arises and persists in a difference of conditions, but in the sense of being itself perpetual difference. It follows that Time, as being created by Motion, also entails perpetual difference: Time is the measure of unceasing Motion, accompanying its course and, as it were, carried along its stream.

In short, the common basis of all Motion is the existence of a progression and an urge from potentiality and the potential to actuality and the actual: everything which has any kind of motion whatsoever derives this motion from a pre-existent potentiality within itself of activity or passivity.

(26) We may now take the various specific types of Motion, such as locomotion, and once again enquire for each one whether it is not to be divided on the basis of direction, up, down, straight, circular- a question already raised; whether the organic motion should be distinguished from the inorganic- they are clearly not alike; whether, again, organic motions should be subdivided into walking, swimming and flight.

Perhaps we should also distinguish, in each species, natural from unnatural motions: this distinction would however imply that motions have differences which are not external. It may indeed be the case that motions create these differences and cannot exist without them; but Nature may be supposed to be the ultimate source of motions and differences alike.

Motions may also be classed as natural, artificial and purposive: "natural" embracing growth and decay; "artificial" architecture and shipbuilding; "purposive" enquiry, learning, government, and, in general, all speech and action.

Again, with regard to growth, alteration and birth, the division may proceed from the natural and unnatural, or, speaking generally, from the characters of the moved objects.

(11) It is intelligible rest that moves material motion in this way, since Cosmos is a sphere - that is to say, a head. And naught of head above's material, as naught of feet below's intelligible, but all material. And head itself is moved in a sphere-like way - that is to say, as head should move, is mind. All then that are united to the "tissue" of this "head" (in which is soul) are in their nature free from death - just as when body hath been made in soul, are things that hath more soul than body. Whereas those things which are at greater distance from this "tissue" - there, where are things which have a greater share of body than of soul - are by their nature subject unto death. The whole, however, is a life; so that the universe consists of both the hylic and of the intelligible.

(9) A: What meanest thou by this, Thrice-greatest one? Is it not bodies, then, that move the stock and stone and all the other things inanimate? H: By no means, O Asclepius. The something-in-the-body, the that-which-moves the thing inanimate, this surely's not a body, for that it moves the two of them - both body of the lifter and the lifted? So that a thing that's lifeless will not move a lifeless thing. That which doth move [another thing] is animate, in that it is the mover. Thou seest, then, how heavy laden is the soul, for it alone doth lift two bodies. That things, moreover, moved are moved in something as well as moved by something is clear.

(17) Tat: Doth not Earth even, father, seem to thee to have no motion? Hermes: Nay, son; but rather that she is the only thing which, though in very rapid motion, is also stable. For how would it not be a thing to laugh at, that the Nurse of all should have no motion, when she engenders and brings forth all things? For 'tis impossible that without motion one who doth engender, should do so. That thou should ask if the fourth part is not inert, is most ridiculous; for the body which doth have no motion, gives sign of nothing but inertia.

(1) But whence that circular movement?

In imitation of the Intellectual-Principle.

And does this movement belong to the material part or to the Soul? Can we account for it on the ground that the Soul has itself at once for centre and for the goal to which it must be ceaselessly moving; or that, being self-centred it is not of unlimited extension , and that its revolution carries the material mass with it?

If the Soul had been the moving power it would be so no longer; it would have accomplished the act of moving and have brought the universe to rest; there would be an end of this endless revolution.

In fact the Soul must be in repose or at least cannot have spatial movement; how then, having itself a movement of quite another order, could it communicate spatial movement?

But perhaps the circular movement is not spatial or is spatial not primarily but only incidentally.

What, by this explanation, would be the essential movement of the kosmic soul?

A movement towards itself, the movement of self-awareness, of self-intellection, of the living of its life, the movement of its reaching to all things so that nothing shall lie outside of it, nothing anywhere but within its scope.

The dominant in a living thing is what compasses it entirely and makes it a unity.

If the Soul has no motion of any kind, it would not vitally compass the Kosmos nor would the Kosmos, a thing of body, keep its content alive, for the life of body is movement.

Any spatial motion there is will be limited; it will be not that of Soul untrammelled but that of a material frame ensouled, an animated organism; the movement will be partly of body, partly of Soul, the body tending to the straight line which its nature imposes, the Soul restraining it; the resultant will be the compromise movement of a thing at once carried forward and at rest.

But supposing that the circular movement is to be attributed to the body, how is it to be explained, since all body, including fire has straightforward motion?

The answer is that forthright movement is maintained only pending arrival at the place for which the moving thing is destined: where a thing is ordained to be, there it seeks, of its nature, to come for its rest; its motion is its tendence to its appointed place.

Then, since the fire of the sidereal system has attained its goal, why does it not stay at rest?

Evidently because the very nature of fire is to be mobile: if it did not take the curve, its straight line would finally fling it outside the universe: the circular course, then, is imperative.

But this would imply an act of providence?

Not quite: rather its own act under providence; attaining to that realm, it must still take the circular course by its indwelling nature; for it seeks the straight path onwards but finds no further space and is driven back so that it recoils on the only course left to it: there is nothing beyond; it has reached the ultimate; it runs its course in the regions it occupies, itself its own sphere, not destined to come to rest there, existing to move.

Further, the centre of a circle is distinctively a point of rest: if the circumference outside were not in motion, the universe would be no more than one vast centre. And movement around the centre is all the more to be expected in the case of a living thing whose nature binds it within a body. Such motion alone can constitute its impulse towards its centre: it cannot coincide with the centre, for then there would be no circle; since this may not be, it whirls about it; so only can it indulge its tendence.

If, on the other hand, the Kosmic circuit is due to the Soul, we are not to think of a painful driving ; the soul does not use violence or in any way thwart nature, for "Nature" is no other than the custom the All-Soul has established. Omnipresent in its entirety, incapable of division, the Soul of the universe communicates that quality of universal presence to the heavens, too, in their degree, the degree, that is, of pursuing universality and advancing towards it.

If the Soul halted anywhere, there the Kosmos, too, brought so far, would halt: but the Soul encompasses all, and so the Kosmos moves, seeking everything.

Yet never to attain?

On the contrary this very motion is its eternal attainment.

Or, better; the Soul is ceaselessly leading the Kosmos towards itself: the continuous attraction communicates a continuous movement- not to some outside space but towards the Soul and in the one sphere with it, not in the straight line , but in the curving course in which the moving body at every stage possesses the Soul that is attracting it and bestowing itself upon it.

If the soul were stationary, that is if it dwelt wholly and solely in the realm in which every member is at rest, motion would be unknown; but, since the Soul is not fixed in some one station There, the Kosmos must travel to every point in quest of it, and never outside it: in a circle, therefore.