The distinction drawn by Aristotle between [Greek: to\ koino\n kat' i)de/an] and [Greek: to\ koino\n kat' a)nalogi/an]--between [Greek: ta\ kata\ mi/an i)de/an lego/mena], and [Greek: ta\ pro\s e(\n] or [Greek: pro\s mi/an phu/sin lego/mena]--this distinction corresponds in part to that which is drawn by Dr. Whewell between classes which are given by Definition, and natural groups which are given by Type. "Such a natural group" (says Dr. Whewell) "is steadily fixed, though not precisely limited; it is given, though not circumscribed; it is determined, not by a boundary but by a central point within, &c." The coincidence between this doctrine and the Aristotelian is real, though only partial: [Greek: to\ prô=ton phi/lon, to\ prô=ton o(rekto/n], may be considered as types of _objects loveable, objects desirable_, &c., but [Greek: ê( u(giei/a] cannot be considered as a type of [Greek: ta\ u(gieina\] nor [Greek: ê( i)atrikê\] as a type of [Greek: ta\ i)atrika/], though it is "the central point" to which all things so called are referred. See Dr. Whewell's doctrine stated in the Philosophy of the Inductive Sciences, i. 476-477; and the comments of Mr. John Stuart Mill on the doctrine--'System of Logic,' Book iv. ch. 7. I have adverted to this same doctrine in remarking on the Hippias Major, supra, p. 47; also on the Philêbus, infra, chap. 32, vol. III.] [Footnote 46: This is attested by Aristotle, Eth. Nik. i. 64, p. 1096, a. 16. [Greek: Oi( de\ komi/santes tê\n do/xan tau/tên, ou)k e)poi/oun i)de/as e)n oi(=s to\ pro/teron kai\ to\ u(/steron e)/legon; dio/per ou)de\ tô=n a)rithmô=n i)de/an kateskeu/azon]: compare Ethic. Eudem. i. 8, 1218, a. 2. He goes on to object that Plato, having laid this down as a general principle, departed from it in recognizing an [Greek: i)de/an a)gathou=], because [Greek: ta)gatho\n] was predicated in all the categories, in that of [Greek: ou)si/a] as well as in that of [Greek: pro/s ti--to\ de\ kath' au(to\ kai\ ê( ou)si/a pro/teron tê=| phu/sei tou= pro/s ti--ô(/ste ou)k a)\n ei)/ê koinê/ tis e)pi\ tou/tôn i)de/a.]] [Side-note: Primum Amabile of Plato, compared with the Prima Amicitia of Aristotle. Each of them is head of an analogical aggregate, not member of a generic family.]