The Categories is a text from Aristotle's Organon that enumerates all
the possible kinds of things that can be the subject or the predicate of
a proposition. They are "perhaps the single most heavily discussed of
all Aristotelian notions". The Categories places every object of human
apprehension under one of ten categories (known to medieval writers as
the Latin term predicament). Aristotle intended them to enumerate
everything that can be expressed without composition or structure, thus
anything that can be either the subject or the predicate of a
proposition. Later texts by scholastic philosophers also reflect this
disparity of treatment.