Chapter IV. The existence of God is proven from the contingency of creatures; since, because they are contingent, a necessary being must exist, by which they exist.

1. First of all, we must here note and distinguish what is the necessary being, and what is the contingent. The necessary being is the one that exists, and cannot but exist, because it has its being from itself and not of its own will, but by necessity of its own nature. And being from itself, it must necessarily be unique, eternal, and most perfect. It must be unique, because otherwise it would not be necessary. It must be eternal: otherwise, being from itself and not from others, it would not have been able to give being to itself, when it was not; because nothingness cannot give being to itself. Moreover it would have been non-existent and existent at the same time: non-existent, because at one time it was not; existent, because it would have had the power of giving existence to itself, and that which has this power, must necessarily exist. Now to exist and exist not at the same time is repugnant to reason. It must also be most perfect, because receiving the supreme perfection of independent existence from itself, it can lack no other perfection; and receiving its being from itself, there is no other power that can limit its perfections. Neither can it limit them for itself, because its perfections are not arbitrary, but absolutely necessary, and intrinsic to its nature. Now, we say that this necessary being is our God.

2. The contingent being, then, is the one that can be or not, indifferently, and therefore needs to be determined to be by others: in such a way that, had not there been a necessary being to determine all contingents beings to be, no being would exist in the present.

3. Now we see many contingent things: trees that sprout and then wither; springs that flow and then dry out; animals that are born and then die; all these contingent things demonstrate the necessity of a necessary being that produced them and determined them to be; otherwise of all that we see, nothing would exist. Let us tighten our argument. It cannot be said that all beings are necessary, nor that all are contingent. It cannot be said that they all be necessary, mainly because it is repugnant to reason that so many different substances exist, all being necessary; secondly because the necessary being, being from itself and lacking any to limit it, as we have seen, is infinitely perfect; but we see down here so many sensible objects, and all of them imperfect; therefore they cannot be necessary. Moreover, as we have said, the necessary being must be eternal, otherwise it would not have been necessary; but we see many things that today are, and before were not, e.g. many children who now live, and a few years ago were nothing. On the other hand it cannot be said that all beings are contingent, because if all things had been contingent before they began existing, they would have been possible and impossible at the same time: possible, because they would be able to receive being from themselves, as in fact so many beings possess being; impossible, because they, being contingent, could not have produced themselves, and there would be no other being to give them being, all beings being contingent. If beings then are not all necessary, or all contingent, we must confess that there is only one necessary being, and that all others which are contingent have been produced by the first one; otherwise there would be no produced being in the world. The argument is clear, and admits no retort.

4. Materialists do not deny, because they cannot, the existence of the necessary being; but they say that this necessary being is the eternal and uncreated matter; they hold that all beings, though produced, did not receive their being from God (who is, as we believe, the necessary being), but from themselves, ab eterno, being produced from eternity in succession, one from the other. So I reply: this eternal matter, considered a producing cause, is nothing else but the selfsame beings producing one another ab eterno. But if this is the case, matter is not the cause of beings, and in fact beings themselves are their own cause. And this cannot be, as we have already replied above, because without a first producing cause there cannot be any produced effect; otherwise these beings produced from one another ab eterno, as we said, would be dependent and independent at the same time: dependent, because none of them would have had its being from itself, but each from another; independent, because the whole of them would not depend from an extrinsic cause, but they would receive their being from themselves.

5. Moreover, if matter had had its being from itself, without being created by an author, it could not have had received motion from itself, because matter is by its nature inert and inactive. So that if all beings of heavens and earth, being material, had not had an extrinsic agent to give them motion, they would have stayed immobile; in such a way that there would be no generation of animals or propagation of plants; trees would not produce fruit; the soil would not produce grass and herbs; there would be no wind or rain; because all this things act by way of motions, and they could not receive this motion from themselves. But we will explain this matter more copiously in the next chapter.

6. Let us resume briefly what we said in this chapter, to conclude that the existence of a God author of all is evident. It cannot be said that all beings are necessary, because if they had all been necessary, being from themselves, they would all be most perfect and eternal; but we see on the contrary many imperfect objects, and temporal, because they were not before, and now they are. Neither can it be said that all beings are contingent, because if they were, there would be no existing being in the world, since no being could have given being to itself. Replying that these beings received their being one from another ab eterno in succession is inane: because they would be effects without a cause, which is impossible, and would be object that move without motion, because matter is by nature inert and idle. Since then beings cannot be all necessary or all contingent, we must necessarily admit a necessary being that has in itself the necessary reason for its independent existence, and the power to give being to all other contingent beings; and this is God, who is the creator and preserver of all creatures, which are contingent.