Next, he distinguishes between a subject of predication, namely that of which anything is affirmed or denied, and a subject of inhesion. A thing is said to be inherent in a subject, when, though it is not a part of the subject, it cannot possibly exist without the subject, e.g., shape in a thing having a shape. The categories are not abstract platonic entities but are found in speech, these are substance, quantity, quality, relation, place, time, position, state, action and affection. In "de Interpretatione", Aristotle analyzes categoric propositions, and draws a series of basic conclusions on the routine issues of classifying and defining basic linguistic forms, such as simple terms and propositions, nouns and verbs, negation, the quantity of simple propositions (primitive roots of the quantifiers in modern symbolic logic), investigations on the excluded middle (which to Aristotle isn't applicable to future tense propositions — the Problem of future contingents), and on modal propositions.