The guide for the perplexed

by Moses Maimonides

The first case, viz., that the moving agent of the sphere is a corporeal object without the sphere, is impossible, as will be explained. Since the moving agent is corporeal, it must itself move while setting another object in motion (Prop. IX.), and as the sixth element would likewise move when imparting motion to another body, it would be set in motion by a seventh element, which must also move. An infinite number of bodies would thus be required before the sphere could be set in motion. This is contrary to Proposition II.

The third case, viz., that the moving object be a force distributed throughout the whole body, is likewise impossible. For the sphere is corporeal, and must therefore be finite (Prop. I.); also the force it contains must be finite (Prop. XII.), since each part of the sphere contains part of the force (Prop. XI.): the latter can consequently not produce an infinite motion, such as we assumed according to Proposition XXVI., which we admitted for the present.

The fourth case is likewise impossible, viz., that the sphere is set in motion by an indivisible force residing in the sphere in the same manner as the soul resides in the body of man. For this force, though indivisible, could not be the cause of infinite motion by itself alone; because if that were the case the prime motor would have an accidental motion (Prop. VI.). But things that move accidentally must come to rest (Prop. VIII.), and then the thing comes also to rest which is set in motion. (The following may serve as a further illustration of the nature of accidental motion. When man is moved by the soul, i.e., by his form, to go from the basement of the house to the upper storey, his body moves directly, while the soul, the really efficient cause of that motion, participates in it accidentally. For through the translation of the body from the basement to the upper storey, the soul has likewise changed its place, and when no fresh impulse for the motion of the body is given by the soul, the body which has been set in motion by such impulse comes to rest, and the accidental motion of the soul is discontinued). Consequently the motion of that supposed first motor must be due to some cause which does not form part of things composed of two elements, viz., a moving agent [[151]]and an object moved; if such a cause is present the motor in that compound sets the other element in motion; in the absence of such a cause no motion takes place. Living beings do therefore not move continually, although each of them possesses an indivisible motive element; because this element is not constantly in motion, as it would be if it produced motion of its own accord. On the contrary, the things to which the action is due are separate from the motor. The action is caused either by desire for that which is agreeable, or by aversion from that which is disagreeable, or by some image, or by some ideal when the moving being has the capacity of conceiving it. When any of these causes are present then the motor acts; its motion is accidental, and must therefore come to an end (Prop. VIII.). If the motor of the sphere were of this kind the sphere could not move ad infinitum. Our opponent, however, holds that the spheres move continually ad infinitum; if this were the case, and it is in fact possible (Prop. XIII.), the efficient cause of the motion of the sphere must, according to the above division, be of the second kind, viz., something incorporeal and separate from the sphere.

It may thus be considered as proved that the efficient cause of the motion of the sphere, if that motion be eternal, is neither itself corporeal nor does it reside in a corporeal object; it must move neither of its own accord nor accidentally; it must be indivisible and unchangeable (Prop. VII. and Prop. V.). This Prime Motor of the sphere is God, praised be His name!

The hypothesis that there exist two Gods is inadmissible, because absolutely incorporeal beings cannot be counted (Prop. XVI.), except as cause and effect; the relation of time is not applicable to God (Prop. XV.), because motion cannot be predicated of Him.

The result of the above argument is consequently this: the sphere cannot move ad infinitum of its own accord; the Prime Motor is not corporeal, nor a force residing within a body; it is One, unchangeable, and in its existence independent of time. Three of our postulates are thus proved by the principal philosophers.

The philosophers employ besides another argument, based on the following proposition of Aristotle. If there be a thing composed of two elements, and the one of them is known to exist also by itself, apart from that thing, then the other element is likewise found in existence by itself separate from that compound. For if the nature of the two elements were such that they could only exist together—as, e.g., matter and form—then neither of them could in any way exist separate from the other. The fact that the one component is found also in a separate existence proves that the two elements are not indissolubly connected, and that the same must therefore be the case with the other component. Thus we infer from the existence of honey-vinegar and of honey by itself, that there exists also vinegar by itself. After having explained this Proposition Aristotle continues thus: We notice many objects consisting of a motor and a motum, i.e., objects which set other things in motion, and whilst doing so are themselves set in motion by other things; such is clearly the case as regards all the middle members of a series of things in motion. We also see a thing that is moved, but does not itself move anything, viz., the last member of the series; consequently a motor must exist without being at the same time a motum, and that is the Prime Motor, which, [[152]]not being subject to motion, is indivisible, incorporeal, and independent of time, as has been shown in the preceding argument.

Third Philosophical Argument.—This is taken from the words of Aristotle, though he gives it in a different form. It runs as follows: There is no doubt that many things actually exist, as, e.g., things perceived with the senses. Now there are only three cases conceivable, viz., either all these things are without beginning and without end, or all of them have beginning and end, or some are with and some without beginning and end. The first of these three cases is altogether inadmissible, since we clearly perceive objects which come into existence and are subsequently destroyed. The second case is likewise inadmissible, for if everything had but a temporary existence all things might be destroyed, and that which is enunciated of a whole class of things as possible is necessarily actual. All things must therefore come to an end, and then nothing would ever be in existence, for there would not exist any being to produce anything. Consequently nothing whatever would exist [if all things were transient]; but as we see things existing, and find ourselves in existence we conclude as follows:—Since there are undoubtedly beings of a temporary existence, there must also be an eternal being that is not subject to destruction, and whose existence is real, not merely possible.

It has been further argued that the existence of this being is necessary, either on account of itself alone or on account of some external force. In the latter case its existence and non-existence would be equally possible, because of its own properties, but its existence would be necessary on account of the external force. That force would then be the being that possesses absolute existence (Prop. XIX.). It is therefore certain that there must be a being which has absolutely independent existence, and is the source of the existence of all things, whether transient or permanent, if, as Aristotle assumes, there is in existence such a thing, which is the effect of an eternal cause, and must therefore itself be eternal. This is a proof the correctness of which is not doubted, disputed, or rejected, except by those who have no knowledge of the method of proof. We further say that the existence of anything that has independent existence is not due to any cause (Prop. X.), and that such a being does not include any plurality whatever (Prop. XXI.); consequently it cannot be a body, nor a force residing in a body (Prop. XXII.). It is now clear that there must be a being with absolutely independent existence, a being whose existence cannot be attributed to any external cause, and which does not include different elements; it cannot therefore be corporeal, or a force residing in a corporeal object; this being is God.

It can easily be proved that absolutely independent existence cannot be attributed to two beings. For, if that were the case, absolutely independent existence would be a property added to the substance of both; neither of them would be absolutely independent on account of their essence, but only through a certain property, viz., that of this independent existence, which is common to both. It can besides be shown in many ways that independent existence cannot be reconciled with the principle of dualism by any means. It would make no difference, whether we imagine two beings of similar or of different properties. The reason for all this is to be sought in the absolute simplicity and in the utmost perfection of the essence of this being, which is [[153]]the only member of its species, and does not depend on any cause whatever; this being has therefore nothing in common with other beings.