 General or abstract ideas are an important class of ideas are derived from ideas of particular things. Although everything that exists is singular, ideas can represent more than one thing. The general idea of a triangle represents all particular triangles. Next, proper nouns which indicate single individuals, such as “Socrates”, “Rome”, “Bucephalus”, are distinguished from common or appellative nouns such as “man”, “city”, “horse”, which can indicate more than one thing. Throughout the text, the authors call both universal ideas and common nouns “general terms.” The mental process yielding the ideas associated with general terms is explained with a geometrical example.