"In addition to developing the hypothetical syllogism, Stoic
logic also elaborated categories, which likewise stand in
contrast to Aristotelian thought. The Stoics teach that there
are four categories: substance, quality, disposition, and
relative disposition.(140) Rather than being horizontal,
signifying aspects of an enduring substance which are accidental
and which can be shorn from it without destroying its essence,
the Stoic categories are vertical. They move from lesser to
greater levels of concreteness. None is accidental; all must be
present in a given reality if that reality is to be grasped in
all its individuality. Substance denotes the materiality of a
thing and is possessed by everything except the incorporeals.
Quality denotes the way in which matter is organized to form an
individual being. Disposition includes times, places, actions,
size, and color. It describes the particular situation and
attributes of the individual. All the features covered by the
category of disposition, including color,