1. Philosophy at a very early stage investigated the number and character of the Existents. Various theories resulted: some declared for one Existent, others for a finite number, others again for an infinite number, while as regards the nature of the Existents- one, numerically finite, or numerically infinite- there was a similar disagreement. These theories, in so far as they have been adequately examined by later workers, may be passed over here; our attention must be directed upon the results of those whose examination has led them to posit on their awn account certain well-defined genera.
These thinkers rejected pure unity on the ground of the plurality observed even in the Intellectual world; they rejected an infinite number as not reconcilable with the facts and as defying knowledge: considering the foundations of being to be "genera" rather than elements strictly so called, they concluded for a finite number. Of these "genera" some found ten, others less, others no doubt more.
But here again there is a divergence of views. To some the genera are first-principles; to others they indicate only a generic classification of the Existents themselves.
Let us begin with the well-known tenfold division of the Existents, and consider whether we are to understand ten genera ranged under the common name of Being, or ten categories. That the term Being has not the same sense in all ten is rightly maintained.
But a graver problem confronts us at the outset: Are the ten found alike in the Intellectual and in the Sensible realms? Or are all found in the Sensible and some only in the Intellectual? All in the Intellectual and some in the Sensible is manifestly impossible.
At this point it would be natural to investigate which of the ten belong to both spheres, and whether the Existents of the Intellectual are to be ranged under one and the same genus with the Existents in the Sensible, or whether the term "Existence" [or Substance] is equivocal as applied to both realms. If the equivocation exists, the number of genera will be increased: if there is no equivocation, it is strange to find the one same "Existence" applying to the primary and to the derivative Existents when there is no common genus embracing both primal and secondary.
These thinkers are however not considering the Intellectual realm in their division, which was not intended to cover all the Existents; the Supreme they overlooked.