 Paul’s world consists of finite beings (that is, things like men or horses) really existing outside the mind, each made up of a primary substance and a host of forms existing in it and by it. The forms of a primary substance belong to ten different types of being, or categories. Therefore a finite being cannot be totally identified with the primary substance. (In fact no primary substance contains the whole being of a finite being.) Rather it is an ordered congeries of categorial items. Primary substances are not simple items but complex objects, since they are compounded of particular matter and form—a form that is really identical with and formally distinct from the specific nature itself that the primary substance instantiates (SN, part VI, chap. 1, fols. 92vb–93ra). The concepts of matter and form are relative, since their meanings are connected with each other (In Post., fol. 40rb). Being the form of something and being the matter of something are converse relations of three different kinds, whose arguments and values are: