So far we have studied being in itself and those modes of it (the transcendental properties) which occur in being universally. With the predicaments - the term "categories" is also much used - we embark upon the study of being in its particular modes, which (as against the universal modes) are really distinct from each other and do not necessarily follow on being simply because it is being. Of these, therefore, we cannot say they are convertible with being.
That there are a number of such modes Aristotle regarded as self-evident. Inductively (consulting experience) he found that the supreme or ultimate genera of being (which are particular modes) came to ten, an enumeration that was to win lasting acceptance among his followers. These ultimate genera, or predicaments, divide first of all into substance and accident, substance denoting being which exists in itself, and accident being which can only exist in another. There are nine distinct modes of accident: quantity, quality, relation, action, passion, place, position, time, and possession.
As was brought out in the chapter on analogy, the predicaments are analogical modes of being. As a matter of fact, Aristotle regarded them as the typical case of the analogy of attribution, in illustration of which health is perennially, and aptly, cited. Medicine, complexion, and so forth are said to be healthy because of their relation to health as it exists in a living thing, specifically in the bodily organism, which alone possesses it formally or properly. Similarly, the various accidents are said to be being by virtue of relation to substance, which is more perfectly being than accidents. But being, as we know, is also analogous by proportionality; consequently, the being of accidents too is being in a formal or proper sense, and not by mere denomination. For all that, however, the primary and fundamental being of the predicamental order is substance, and that is why we shall give it more attention.
Some incidental matters should first be set down. In their totality (for one), the predicaments cannot be said of every order of being, but only of material beings. Quantity and whatever relates to quantity has obviously no place in the world of spiritual substances. And (for another), the predicamental division of being as St. Thomas conceives of it applies only to creatures; God remains outside or above it. Hence to define him as a substance, while not unheard-of, is none the less unsound - though even Aristotle is somewhat less than clear on the point.