Elsewhere, in Metaphysics (998b22), Aristotle argues explicitly that there cannot be a highest genus (e.g., of being or unity) shared by entities of different categories (cf. Ackrill 1963, 81).
In the first lines of the eighth chapter of the Categories (8a25 26) Aristotle observes that quality is among those things that are spoken of in a number of ways an affirmation which seems to imply that quality is not a highest genus, as, according to Aristotle himself, what is spoken of in a number of ways always gathers in several different natures.
We study certain finite dimensional reproducing kernel indefinite inner product spaces of multiplicative half order differentials on a compact real Riemann surface; these spaces are analogues of the spaces introduced by L. de Branges when the Riemann sphere is replaced by a compact real Riemann surface of a higher genus.
Something is in a category by reduction large if and only if it is an aggregate, and the highest genus of a certain category is predicated only indirectly of it.
Alyngton tries to meet this difficulty by reformulating the notion of quantified-thing (quantum), and by proposing a method for deducing the seven species of quantity from the highest genus (a sort of sufficientia quantitatum).
Consequently, he inserts an intermediate level between the highest genus of the category and the four species by claiming that quality is first of all divided into perceptible (sensibilis) and non-perceptible (insensibilis) qualities.
This is problematic, however, for if the highest genus of the category is a form, Aristotle's seven species of quantity (line, surface, solid, time, space, number, and speech), mentioned in the sixth chapter of the Categories, are not.
Something is in a category by itself if and only if the highest genus of that category is predicated by itself and and directly (in recto) of it (In Cat., cap. de numero et sufficientia praedicamentorum, p. 259).
If the highest genus of the category of quantity is a form, the seven species Aristotle enumerates (line, surface, solid, time, place, number, and speech) clearly are not.
That is why the Stoics think that Something is the highest genus: everything is something.
This 'outflowing' (proodos; processio, exitus) creates the whole universe from the highest genus to the lowest species and 'individuals' (atoma).
