[Footnote 71: Aristot. Metaphys. iv. 1015-1017, ix. 1052, a. 15; Anal. Poster. ii. p. 92, b. 14. [Greek: to\ d' ei)=nai ou)k ou)si/a ou)deni/. ou) ga\r ge/nos to\ o)/n.]--Topica, iv. p. 127, a. 28. [Greek: plei/ô ga\r ta\ pa=sin e(po/mena; oi(=on to\ o)\n kai\ to\ e(\n tô=n pa=sin e(pome/nôn e)/stin], Physica, i. p. 185, b. 6.
Simplikius noted it as one among the differences between Plato and Aristotle--That Plato admitted Unum as having only one meaning, not being aware of the diversity of meanings which it bore; while Aristotle expressly pointed it out as a [Greek: pollakô=s lego/menon] (Schol. ad Aristot. Sophist. Elench. p. 320, b. 3, Brandis). Aristotle farther remarks that Plato considered [Greek: to\ ge/nos] as [Greek: e(\n a)rithmô=|], and that this was an error; we ought rather to say that Plato did not clearly discriminate [Greek: e(\n a)rithmô=|] from [Greek: e(\n ei)/dei] (Aristot. Topic. vi. 143, b. 30).
Simplikius farther remarks, that it was Aristotle who first rendered to Logic the important service of bringing out clearly and emphatically the idea of [Greek: to\ o(mô/numon]--the same word with several meanings either totally distinct and disparate, or ramifying in different directions from the same root, so that there came to be little or no affinity between many of them. It was Aristotle who first classified and named these distinctions ([Greek: sunô/numon--o(mô/numon], and the intermediate [Greek: kat' a)nalogi/an]), though they had been partially noticed by Plato and even by Sokrates. [Greek: e(/ôs A)ristote/lous ou) pa/mpan e)/kdêlon ê)=n to\ o(mô/numon; a)lla\ Pla/tôn te ê)/rxato peri\ tou/tou ê)\ ma=llon e)kei/nou Sôkra/tês], Schol. ad Aristot. Physic. p. 323, b. 24, Brandis.]
[Side-note: In the Platonic Demonstrations the same proposition in words is made to bear very different meanings.]
Certainly, in Demonstrations 1 and 2 (as well as 4 and 5), the foundation assumed is in words the same proposition--_Si Unum est_: but we shall find this same proposition used in two very different senses. In the first Demonstration, the proposition is equivalent to _Si Unum est Unum_:[72] in the second, to _Si Unum est Ens_, or _Si Unum existit_. In the first the proposition is identical and the verb _est_ serves only as copula: in the second, the verb _est_ is not merely a copula but implies Ens as a predicate, and affirms existence. We might have imagined that the identical proposition--_Unum est Unum_--since it really affirms nothing--would have been barren of all consequences: and so indeed it is barren of all affirmative consequences. But Plato obtains for it one first step in the way of negative predicates--_Si Unum est Unum, Unum non est Multa_: and from hence he proceeds, by a series of gentle transitions ingeniously managed, to many other negative predications respecting the subject _Unum_. Since it is not Multa, it can have no parts, nor can it be a whole: it has neither beginning, middle, nor end: it has no boundary, or it is boundless: it has no figure, it is neither straight nor circular: it has therefore no place, being neither in itself, nor in anything else: it is neither in motion nor at rest: it is neither the same with anything else, nor the same with itself:[73] it is neither different from any thing else, nor different from itself: it is neither like, nor unlike, to itself, nor to anything else: it is neither equal, nor unequal, to itself nor to any thing else: it is neither older nor younger, nor of equal age, either with itself or with anything else: it exists therefore not in time, nor has it any participation with time: it neither has been nor will be, nor is: it does not exist in any way: it does not even exist so as to be Unum: you can neither name it, nor reason upon it, nor know it, nor perceive it, nor opine about it.