Genus: a universal predicated in answer to “What is it?” of beings differing in their specific essences.
Real species: a universal similarly predicated of individuals agreeing in specific essence.
Relative species: a narrower nature situated beneath a wider genus alongside other kinds.
Relation between real and relative species: partial overlap.
Ranks of genera: highest, intermediate and lowest.
Do not merely memorize the labels. In each example identify the relevant items, whether their natures agree or differ, and the genus or species immediately above or below.
The next section turns to the highest genera and ten categories.