Chapter 36
Chapter 36 Solution of the Arguments Alleged on the Part of the Things Produced Likewise there is nothing on the part of creatures that necessarily induces us to assert their eternity.35
The necessity of existing which is found in creatures and is the basis of the first argument for this position, is a necessity of order, as was shown previously.3" But the necessity of order does not force the thing (hat is subject to such necessity to have existed forever, as was pointed out above.37 Although the substance of heaven necessarily exists, since it lacks potentiality to non-existence, this necessity is consequent on its substance. Therefore, once heaven's substance has been brought into being, this necessity entails the impossibility of not existing; but if the production of its substance is taken into considera tion, such necessity does not obviate heaven's non-existence.
Similarly, the power of existing always, from which the second argument was drawn, presupposes the production of the substance.
Therefore, since the production of the substance of heaven is in ques tion, such power cannot be a conclusive argument for the eternity of that substance.
The objection next adduced does not compel us to acknowledge the eternity of motion. It is plain from the preceding chapter that without any change in Himself, God the agent can accomplish some thing new, something that is not eternal. But if something can be done by Him anew, it is clear that something can also be put in motion by Him anew, for newness of motion follows on the decision of the eternal will that motion is not to be eternal.
Likewise, the tendency of natural agents to perpetuate their species, which was the source of the fourth argument, presupposes that natural agents have already been produced. Hence this argu ment is out of place except with regard to natural things that have already been brought into being; it is irrelevant when there is ques tion of the production of these things. Whether a process of genera tion that will go on forever has to be admitted, will be examined later.38
Also the fifth argument, based on time, presupposes rather than proves the eternity of motion. According to Aristotle's teaching, the before and after and continuity of time are dependent on the before and after and continuity of motion;30 hence the same instant is
38 Book IV, chap. 97.
33 Physics, IV, 11 (219a 17).
35 Cf. chap. 33.
36 Chap. 30.
37 Chap. 31.
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clearly the beginning of the future and the end of the past, because some assignable point in motion is the beginning and end of the various segments of motion. Not every instant, therefore, will have to be of this kind, unless every assignable point in time is taken to be midway between before and after in motion—which is to suppose that motion is eternal. But if we suppose that motion is not eternal, we can say that the first instant of time is the beginning of the future without being the end of any past. Nor is the contention that some now is a beginning and not an end incompatible with the succession of time, on the ground that a line, in which a point is placed as a beginning and not an end, is stationary and not transitory; for even in a particular movement, which of course is not stationary but transi tory, some point can be designated as only the beginning without being the end of movement. Otherwise all motion would be per petual, which is impossible.
In the hypothesis that time began, the assertion that it did not exist before it existed does not compel us to admit that the very sup position of its non-existence implies its existence, as the sixth argu ment inferred. For the before we speak of as preceding time does not imply any flight of time in reality, but only in our imagination. When we say that time exists after not existing, we mean that no time was flowing prior to this designated now. In the same way, when we say that there is nothing above heaven, we do not mean that there is some place beyond heaven which may be said to be above in relation to it, but that there is no place higher than heaven. In both cases the imagination can add a certain dimension to the existing thing. How ever, just as such addition is no reason for attributing infinite quantity to a body, as is indicated in Book III of the Physics,40 so neither is it a reason for admitting that time is eternal.
The truth of the propositions which even the one who denies the propositions must concede, as maintained in the seventh argument, involves the necessity of the order which exists between predicate and subject. Such necessity does not require a thing to exist forever, ex cept, indeed, the divine intellect, in which all truth is rooted, as was shown in Book I.41
Clearly, therefore, the arguments derived from creatures do not compel us to assert the eternity of the world.
40 Aristotle, Physics, III, 6 (206b 20). 41 Chap. 62.
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