Lives of Eminent Philosophers 7.61 — Diogenes Laërtius on the Stoics

Diogenes Laërtius, Lives of Eminent Philosophers 7.61

Reported speech · Diogenes Laërtius on the Stoics

A notion or object of thought is a presentation to the intellect, which though not really substance nor attribute is quasi-substance or quasi-attribute. Thus an image of a horse may rise before the mind, although there is no horse present. Species is that which is comprehended under genus: thus Man is included under Animal. The highest or most universal genus is that which, being itself a genus, has no genus above: namely, reality or the real; and the lowest and most particular species is that which, being itself a species, has no species below it, e.g. Socrates. Division of a genus means dissection of it into its proximate species, thus: Animals are either rational or irrational (dichotomy). Contrary division dissects the genus into species by contrary qualities: for example, by means of negation, as when all things that are are divided into good and not good. Subdivision is division applied to a previous division: for instance, after saying, “Of things that are some are good, some are not good,” we proceed, “and of the not good some are bad, some are neither good nor bad (morally indifferent).”