Commentary on Aristotle's Physics

 CONTENTS

 TRANSLATORS' PREFACE

 INTRODUCTION

 BOOK I

 LECTURE 1 (184 a 9-b 14)

 LECTURE 2 (184 b 15-185 a 19)

 LECTURE 3 (185 a 20-b 27)

 LECTURE 4 (185 b 27-186 a 4)

 LECTURE 5 (186 a 5-22)

 LECTURE 6 (186 a 23-b 35)

 LECTURE 7 (187 a 1-10)

 LECTURE 8 (187 a 11-26)

 LECTURE 9 (187 a 27-188 a 18)

 LECTURE 10 (188 a 19-189 a 10)

 LECTURE 11 (189 a 11-b 29)

 LECTURE 12 (189 b 30-190 b 15)

 LECTURE 13 (190 b 16-191 a 22)

 LECTURE 14 (191 a 23-b 34)

 LECTURE 15 (191 b 35-192 b 5)

 BOOK II

 LECTURE 1 (192 b 8-193 a 8)

 LECTURE 2 (193 a 9-b 21)

 LECTURE 3 (193 b 22-194 a 11)

 LECTURE 4 (194 a 12-b 15)

 LECTURE 5 (194 b 16-195 a 27)

 LECTURE 6 (195 a 28-b 30)

 LECTURE 7 (195 b 31-196 b 9)

 LECTURE 8 (196 b 10-197 a 7)

 LECTURE 9 (197 a 8-35)

 LECTURE 10 (197 a 36-198 a 21)

 LECTURE 11 (198 a 22-b 9)

 LECTURE 12 (198 b 10-33)

 LECTURE 13 (198 b 34-199 a 33)

 LECTURE 14 (199 a 34-b 33)

 LECTURE 15 (199 b 34-200 b 9)

 BOOK III

 LECTURE 1 (200 b 12-201 a 8)

 LECTURE 2 (201 a 9-b 5)

 LECTURE 3 (201 b 6-202 a 2)

 LECTURE 4 (202 a 3-21)

 LECTURE 5 (202 a 22-b 29)

 LECTURE 6 (202 b 30-203 b 14)

 LECTURE 7 (203 b 15-204 b 3)

 LECTURE 8 (204 b 4-205 a 6)

 LECTURE 9 (205 a 7-206 a 7)

 LECTURE 10 (206 a 8-b 32)

 LECTURE 11 (206 b 33-207 a 31)

 LECTURE 12 (207 a 32-208 a 4)

 LECTURE 13 (208 a 5-24)

 BOOK IV

 LECTURE 1 (208 a 27-209 a 1)

 LECTURE 2 (209 a 2-30)

 LECTURE 3 (209 a 31-210 a 13)

 LECTURE 4 (210 a 14-b 32)

 LECTURE 5 (210 b 33-211 b 4)

 LECTURE 6 (211 b 5-212 a 30)

 LECTURE 7 (212 a 31-b 22)

 LECTURE 8 (212 b 23-213 a 10)

 LECTURE 9 (213 a 11-b 20)

 LECTURE 10 (213 b 30-214 b 11)

 LECTURE 11 (214 b 12-215 a 23)

 LECTURE 12 (215 a 24-216 a 26)

 LECTURE 13 (216 a 27-216 b 20)

 LECTURE 14 (216 b 21-217 b 28)

 LECTURE 15 (217 b 29-218 a 30)

 LECTURE 16 (218 a 31-219 a 1)

 LECTURE 17 (219 a 2-b 8)

 LECTURE 18 (219 b 9-220 a 23)

 LECTURE 19 (220 a 24-b 30)

 LECTURE 20 (221 a 1-222 a 9)

 LECTURE 21 (222 a 10-b 15)

 LECTURE 22 (222 b 16-223 a 15)

 LECTURE 23 (223 a 16-224 a 16)

 BOOK V

 LECTURE 1 (224 a 21-b 34)

 LECTURE 2 (224 b 35-225 b 4)

 LECTURE 3 (225 b 5-226 a 22)

 LECTURE 4 (226 a 23-b 18)

 LECTURE 5 (226 b 19-227 b 2)

 LECTURE 6 (227 b 3-228 a 19)

 LECTURE 7 (228 a 20-229 a 6)

 LECTURE 8 (229 a 7-b 22)

 LECTURE 9 (229 b 23-230 a 18)

 LECTURE 10 (230 a 19-231 a 18)

 BOOK VI

 LECTURE 1 (231 a 21-b 18)

 LECTURE 2 (231 b 19-232 a 18)

 LECTURE 3 (232 a 19-233 a 16)

 LECTURE 4 (233 a 17-b 32)

 LECTURE 5 (233 b 33-234 b 20)

 LECTURE 6 (234 b 21-235 b 5)

 LECTURE 7 (235 b 6-236 b 19)

 LECTURE 8 (236 b 20-237 b 23)

 LECTURE 9 (237 b 24-238 b 22)

 LECTURE 10 (238 b 23-239 b 4)

 LECTURE 11 (239 b 5-240 b 7)

 LECTURE 12 (240 b 8-241 a 26)

 LECTURE 13 (241 a 27-b 20)

 BOOK VII

 LECTURE 1 (241 b 24-242 a 15)

 LECTURE 2 (242 a 16-243 a 2)

 LECTURE 3

 LECTURE 4

 LECTURE 5

 LECTURE 6

 LECTURE 7 (248 a 10-249 a 7)

 LECTURE 8 (249 a 8-b 25)

 LECTURE 9 (249 b 26-250 b 9)

 BOOK VIII

 LECTURE 1 (250 b 11-251 a 7)

 LECTURE 2 (251 a 8-252 a 3)

 LECTURE 3 (252 a 4-b 6)

 LECTURE 4 (252 b 7-253 a 21)

 LECTURE 5 (253 a 22-254 a 2)

 LECTURE 6 (254 a 3-b 6)

 LECTURE 7 (254 b 7-255 a 18)

 LECTURE 8 (255 a 19-256 a 2)

 LECTURE 9 (256 a 3-257 a 34)

 LECTURE 10 (257 a 35-258 a 5)

 LECTURE 11 (258 a 6-b 9)

 LECTURE 12 (258 b 10-259 a 21)

 LECTURE 13 (259 a 22-260 a 19)

 LECTURE 14 (260 a 20-261 a 27)

 LECTURE 15 (261 a 28-b 26)

 LECTURE 16 (261 b 27-262 b 9)

 LECTURE 17 (262 b 10-264 a 7)

 LECTURE 18 (264 a 8-b 8)

 LECTURE 19 (264 b 9-265 a 27)

 LECTURE 20 (265 a 28-266 a 9)

 LECTURE 21 (266 a 10-b 26)

 LECTURE 22 (266 b 27-267 a 21)

 LECTURE 23 (267 a 22-b 26)

 APPENDIX A

 BOOK VII, CHAPTER 2

 BOOK VII, CHAPTER 3

 Footnotes

LECTURE 3 (252 a 4-b 6)

ARGUMENTS AGAINST ANAXAGORAS AND EMPEDOCLES WHO HELD THAT MOTION IS NOT ETERNAL

             991. After the Philosopher has given arguments to show that motion is eternal, he here gives arguments against Anaxagoras and Empedocles who held the contrary.

             Concerning this he makes two points. First he gives an argument against their position. Secondly, where he says, 'And much the same . . .' (252 a 5), he argues against the argument which they used.

             He says, therefore, first that since it has been shown that motion is eternal, it should not be said that sometimes there is motion and sometimes there is not, as Empedocles and Anaxagoras maintained. For to say what they said is comparable to fiction, because they held this without reason. Everything which is held without reason or without divine authority seems to be fiction. Divine authority, however, prevails over human reason much more than the authority of a philosopher prevails over some feeble argument which is offered by a boy.

             What we hold through faith is not to be compared to fiction, even though we believe without reason. For we believe on divine authority, which is attested to by miracles, that is, by those works which only God can perform.

             992. Next where he says, 'And much the same . . .' (252 a 5), he objects to the argument which they used.

             Concerning this he makes three points. First he states that their argument is inconsistent. Secondly, where he says, 'But that which is produced . . .' (252 a 11), he shows that the argument is more inconsistent in regard to Anaxagoras' position than in regard to Empedocles' position. Thirdly, where he says, 'But even here the holder . . .' (252 a 22), he shows that it is not consistent according to the opinion of Empedocles.

             He says, therefore, first that there also seems to be a fiction if one were to say that sometimes there is motion and sometimes not because this is natural and must be taken as a principle. Now Empedocles seems to say that things necessarily are such that at one time they have friendship, at another time they have strife and are moved, and in the intermediate time they are at rest. It is as if one were to say that the reason why a warm thing heats is that this must be so, and the fact that a warm thing heats is taken as a principle.

             In the same way Empedocles holds as a principle that things necessarily are such that sometimes they are moved by friendship, sometimes by strife, and sometimes they are at rest.

             And perhaps in the same way Anaxagoras and all others who posit one active principle would say that it must be taken as a principle that motion began after an infinite time in which it was not.

             993. Next where he says, 'But that which is produced . . .' (252 a 11), he shows that Anaxagoras used this argument more inconsistently than Empedocles.

             It is clear that when something is given as a principle, it ought to be in accordance with the nature of the thing, that is, the nature of the thing should be such that it is consistent with it. For example, we accept as a principle that every whole is greater than its parts, because the meaning [ratio] and nature of a whole is such that it exceeds the quantity of a part. Now when Empedocles says, '. . . such is the ordinance of nature . . .' (252 a 5), he means 'this must be taken as a principle'. And Anaxagoras would say the same thing, although he does not express it.

             Now it is clear that no natural thing nor anything which naturally agrees with things can exist without order. For nature is the cause of order. For we see that nature in its own operations proceeds in an orderly way from one to another. Therefore, that which has no order and which is not according to nature cannot be taken as a principle.

             But two infinites do not have an order to each other. For there is no proportion of infinite to infinite. And every order is a certain proportion. Therefore, it is clear that it is not the work of nature for a thing to be at rest in an infinite time, and later begin to be moved through an infinite time, without any difference between this time and that so that the motion occurs now rather than before; nor is it the work of nature for there to be no order between two things of which when one fails the other begins and motion occurs, as Anaxagoras held. For whatever is in nature is always related in the same way, and is not at one time related in one way and at another time in another way. For example, fire is always borne upward. Or else there is some reason why it is not related in the same way. For example, animals do not always increase. Rather they are sometimes diminished, but there is a reason for this.

             Therefore, it does not seem to be in accord with nature that in an infinite time things were at rest and later began to be moved, as Anaxagoras held.

             And so it is better to say, as Empedocles said, or as others have thought, that the whole universe is at rest during one period of time and then it is moved during another period of time. For this may have some order, since there is a proportion of finite to finite.

             Moreover, it must be realized that the belief of our faith is not similar to the position of Anaxagoras. For we do not hold that before the world there were infinite spaces of time which must have a proportion to the following time. Rather we hold that before the world began there was only the simple eternity of God, as was said, which is totally outside the genus of time.

             994. Next where he says, 'But even here the holder . . .', he shows that the previous argument is not consistent even for Empedocles.

             First he explains his position. Secondly, where he says, 'But it is a wrong . . .' (252 a 32), he rejects a certain false opinion.

             He says, therefore, first that anyone who asserts what Empedocles said ought not only to affirm what he says, but should also give a reason for his statement. He should add nothing more than the given reason requires, and he should be unwilling to accept something as a principle without proof. And to clarify what he accepts as a principle he should add either an induction, which is given for natural principles which are derived from the experience of sensible things, or a demonstration, which is given for principles which are demonstrated by prior principles. But Empedocles pays no attention to this. Even though he posits friendship and strife as causes, nevertheless, friendship and strife do not have such a nature [ratio] that one of them moves after the other. Nor is the nature [ratio] of friendship such that it is converted into strife, or vice versa. Rather the nature [ratio] of friendship is such that it unites, and the nature [ratio] of strife is such that it separates.

             And if it is to be determined further that in one part of time one of these unites and in another part of time the other separates, this must be made clear in particular cases. The fact that friendship unites and strife separates is clear in men because friendship brings men together and strife drives them apart. Therefore, Empedocles assumes this for the whole universe because it seems to be so in some cases. But his point that friendship and strife move successively in equal times needs some clarifying reason, for this does not seem to occur in men.

             995. Next where he says, 'But it is a wrong . . .' (252 a 32), he rejects a certain false opinion. One might think that whatever always is does not have a cause because we see that the things among us which are caused begin anew. And therefore in other cases it would seem that whenever a question is reduced to something which always is, it is not necessary to seek a further cause or reason. Therefore, Empedocles could say that friendship and strife always move according to equal times, and hence another reason for this need not be sought. Aristotle rejects this by saying that it is not correct to think that something is a principle because it always is or always occurs. Democritus reduced all natural causes to this by assigning a principle to things which come to be anew, but he did not wish to seek a principle for that which is eternal.

             In some cases this is correct, but not in all cases. It is clear that a triangle always has three angles equal to two right angles; but there is a cause of this enduring quality. But there are some perpetual things, for example, principles, which have no cause.

             996. What is said here should be noted well. For as is said in Metaphysics, II, the disposition of things in being and in truth is the same. Hence just as some things are always true and yet have a cause of their truth, so Aristotle thought that some beings are eternal, namely, celestial bodies and separated substances, but nevertheless they have a cause of their being.

             From this is it clear that, although Aristotle held that the world is eternal, he did not believe that God is the cause only of the motion of the world and not its being, as some have said.

             Finally, he concludes to his main point in an epilogue. He says that these things have been said to show that there will be no time in the future, nor was there a time in the past, in which there is no motion.