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 11 (189 a 11-b 29)

THERE ARE THREE PRINCIPLES OF NATURAL THINGS, NO MORE, NO LESS

             82. After the philosopher has investigated the contrariety of the principles, he here begins to inquire about their number.

             Concerning this he makes three points. First, he raises the question. Secondly, where he says, 'One they cannot be . . .' (189 a 12), he excludes certain things which are not pertinent to this question. Thirdly, he takes up the question, where he says, 'Granted, then, that . . .' (189 a 21).

             He says, therefore, first that after an investigation into the contrariety of the principles, an inquiry about their number should follow, i.e., whether they are two, or three, or more.

             83. Next where he says, 'One they cannot be . . .' (189 a 12), he excludes those things which are not pertinent to this question. He shows first that there is not just one principle, and secondly, where he says, 'Nor can they be . . .' (189 a 12), he shows that the principles are not infinite.

             He says first that it is impossible for there to be only one principle. For it has been shown that the principles are contraries. But contraries are not just one, for nothing is the contrary of itself; therefore, there is not just one principle.

             84. Next where he says, 'Nor can they be . . .' (189 a 12), he gives four arguments to show that the principles are not infinite. The first of these is as follows.

             The infinite as such is unknown. If, therefore, the principles are infinite, they must be unknown. But if the principles are unknown, then those things which are from the principles are unknown. It follows, therefore, that nothing in the world could be known.

             85. He gives the second argument where he says, '. . . and in any one genus . . .' (189 a 13). The argument is as follows. The principles must be primary contraries, as was shown above. But the primary contraries belong to the primary genus, which is substance. But substance, since it is one genus, has one primary contrariety. For the first contrariety of any genus is that of the primary differentiae by which the genus is divided. Therefore, the principles are not infinite.

             86. He gives the third argument where he says, '. . . also a finite number . . .' (189 a 15). The argument is as follows. It is better to say that what can come to be from finite principles comes from finite principles rather than from infinite principles. But all things which come to be according to nature are explained by Empedocles through finite principles, just as they are explained by Anaxagoras through infinite principles. Hence an infinite number of principles should not be posited.

             87. He gives the fourth argument where he says, 'Lastly, some contraries . . .' (189 a 17). The argument is as follows. Principles are contraries. If, therefore, the principles are infinite, it is necessary that all the contraries be principles. But all of the contraries are not principles. This is clear for two reasons. First, the principles must be primary contraries, but not all contraries are primary, since some are prior to others. Secondly, the principles ought not to be from each other, as was said above. But some contraries are from each other, as the sweet and the bitter, and the white and the black. Therefore, the principles are not infinite.

             Thus he finally concludes that the principles are neither one nor infinite.

             88. However, we must note that the Philosopher proceeds here by way of disputation from probable arguments. Hence he assumes certain things which are seen in many instances, and which cannot be false taken as a whole, but are true in particular instances. Therefore, it is true that in a certain respect contraries do come to be from each other, as was said above, if the subject is taken along with the contraries. For that which is white later becomes black. However, whiteness itself is never changed into blackness. But some of the ancients, without including the subject, held that the primary contraries come to be from each other. Hence, Empedocles denied that the elements come to be from each other. And thus Aristotle significantly does not say in this place that the hot comes to be from the cold, but the sweet from the bitter and the white from the black.

             89. Next where he says, 'Granted then . . .' (189 a 21), he takes up the question under discussion, namely, what is the number of the principles. Concerning this he makes two points. First he shows that there are not just two principles, but three. Secondly, where he says, 'On the other hand . . .' (189 b 18), he shows that there are no more than three principles.

             Concerning the first part he makes two points. First, he shows through arguments that there are not just two principles, but that a third must be added. Secondly, where he says, 'If, then, we accept . . .' (189 a 34), he shows that even the ancient philosophers agreed on this point.

             90. Concerning the first part he gives three arguments. He says first that since it was shown that the principles are contraries, and so could not be just one, but are at least two, and further since the principles are not infinite, then it remains for us to consider whether there are only two principles or more than two. Since it was shown above that the principles are contraries, it seems that there are only two principles, because contrariety exists between two extremes.

             But one might question this. For it is necessary that other things come to be from the principles, as was said above. If, however, there are only two contrary principles, it is not apparent how all things can come to be from these two. For it cannot be said that one of them makes something from the other one. For density is not by nature such that it can convert rarity into something, nor can rarity convert density into something. And the same is true of any other contrariety. For friendship does not move strife and make something out of it, nor does the converse happen. Rather each of the contraries changes some third thing which is the subject of both of the contraries. For heat does not make coldness itself to be hot, but makes the subject of coldness to be hot. And conversely, coldness does not make heat itself to be cold, but makes the subject of heat to be cold. Therefore, in order that other things can come to be from the contraries, it seems that it is necessary to posit some third thing which will be the subject of the contraries.

             It does not matter for the present whether that subject is one or many. For some have posited many material principles from which they prepare the nature of beings. For they said that the nature of things is matter, as will be said later in Book II.

             91. He gives the second argument where he says, 'Other objections . . .' (189 a 28). He says that, unless there is something other than the contraries which are given as principles, then there arises an even greater difficulty. For a first principle cannot be an accident which is predicated of a subject. For since a subject is a principle of the accident which is predicated of it and is naturally prior to the accident, then if the first principle were an accident predicated of a subject, it would follow that what is 'of' a principle would be a principle, and there would be something prior to the first. But if we hold that only the contraries are principles, it is necessary that the principles be an accident predicated of a subject. For no substance is the contrary of something else. Rather contrariety is found only between accidents. It follows, therefore, that the contraries cannot be the only principles.

             Moreover, it must be noted that in this argument he uses 'predicate' for 'accident', since a predicate designates a form of the subject. The ancients, however, believed that all forms are accidents. Hence he proceeds here by way of disputation from probable propositions which were well known among the ancients.

             92. He gives the third argument where he says, 'Again we hold . . .' (189 a 33). The argument is as follows. Everything which is not a principle must be from principles. If, therefore, only the contraries are principles, then since substance is not the contrary of substance, it follows that substance would be from non-substance. And thus what is not substance is prior to substance, because what is from certain things is posterior to them. But this is impossible. For substance which is being per se is the first genus of being. Therefore, it cannot be that only the contraries are principles; rather it is necessary to posit some other third thing.

             93. Next where he says, 'If, then, we accept . . .' (189 a 34), he shows how the position of the philosophers also agrees with this.

             Concerning this he makes two points. First, he shows how they posited one material principle. Secondly, where he says, 'All, however agree . . .' (189 b 9), he shows how they posited two contrary principles besides this one material principle.

             However, we must first note that the Philosopher in the preceding arguments seemed to be opposed, in the manner of those who dispute, to both sides of the question. For first he proved that the principles are contraries, and now he brings forth arguments to prove that the contraries are not sufficient for the generation of things. And since disputatious arguments do come to some kind of true conclusion, though it is not the whole [truth], he concludes one truth from each argument.

             He says that if someone thinks that the first argument (which proves that the principles are contraries) is true, and that the argument just given (which proves that contrary principles are not sufficient) is also true, then to maintain both conclusions he must say that some third thing lies beneath the contraries, as was said by those who held that the whole universe is some one nature, understanding nature to mean matter, such as water, or fire or air, or some intermediate state between these, such as vapour, or some other thing of this sort.

             This seems especially true in regard to an intermediate. For this third thing is taken as the subject of the contraries, and as distinct from them in some way. Hence, that which has less of the nature of a contrary about it is more conveniently posited as the third principle beyond the contraries. For fire and earth and air and water have contrariety attached to them, e.g., the hot and the cold, the wet and the dry. Hence, it is not unreasonable that they make the subject something other than these and something in which the contraries are less prominent. After these philosophers, however, those who held that air was the principle spoke more wisely, for the contrary qualities found in air are less sensible. After these philosophers are those who held that water was the principle. But those who held that fire was the principle spoke most poorly, because fire has a contrary quality which is most sensible and which is very active. For in fire there is an excellence of heat. If, however, the elements are compared with reference to their subtlety, those who made fire the principle seem to have spoken better, as is said elsewhere, for what is more subtle seems to be more simple and prior. Hence no one held that earth was the principle because of its density.

             94. Next where he says, 'All, however, agree . . .' (189 b 9), he shows how they posited contrary principles with the one material principle.

             He says that all who posited one material principle said that it is figured or formed by certain contraries, such as rarity and density, which are reducible to the great and the small and to excess and defect. And thus the position of Plato that the one and the great and the small are the principles of things was also the opinion of the ancient natural philosophers, but in a different way. For the ancient philosophers, thinking that one matter was differentiated by diverse forms, held two principles on the part of form, which is the principle of action, and one on the part of matter, which is the principle of passion. But the Platonists, thinking that many individuals in one species are distinguished by a division of matter, posited one principle on the part of the form, which is the active principle, and two on the part of the matter, which is the passive principle.

             And thus he draws the conclusion which he had uppermost in mind, namely, that by considering the above and similar positions, it seems reasonable that there are three principles of nature. And he points out that he has proceeded from probable arguments.

             95. Next where he says, 'On the other hand . . .' (189 b 18), he shows that there are no more than three principles. He uses two arguments, the first of which is as follows.

             It is superfluous for that which can come to be through fewer principles to come to be through many. But the whole generation of natural things can be achieved by positing one material principle and two formal principles. For one material principle is sufficient to account for passion.

             But if there were four contrary principles, and two primary contrarieties, it would be necessary that each contrariety have a different subject. For it seems that there is one primary subject for any one contrariety. And so, if, by positing two contraries and one subject, things can come to be from each other, it seems superfluous to posit another contrariety. Therefore, we must not posit more than three principles.

             96. He gives the second argument where he says, 'Moreover it is impossible . . .' (189 b 23). If there are more than three principles, it is necessary that there be many primary contrarieties. But this is impossible because the first contrariety seems to belong to the first genus, which is one, namely, substance. Hence all contraries which are in the genus of substance do not differ in genus, but are related as prior and posterior. For in one genus there is only one contrariety, namely, the first, because all other contrarieties seem to be reduced to the first one. For there are certain first contrary differentiae by which a genus is divided. Therefore it seems that there are no more than three principles.

             It must be noted, however, that each of the following statements is probable: namely, that there is no contrariety in substances, and that in substances there is only one primary contrariety. For if we take substance to mean 'that which is', it has no contrary. If, however, we take substance to mean formal differentiae in the genus of substance, then contrariety is found in them.

             97. Finally by way of summary he concludes that there is not just one principle, nor are there more than two or three. But deciding which of these is true, that is, whether there are only two principles or three, involves much difficulty, as is clear from the foregoing.