W. rejects his former belief that a unifying essence underlies the endless variety of kinds of uses of language. For those uses of language, he introduces the notion 'language games' ('Sprachspiele') to indicate that language is essentially part of people's activities, a form of life. To explain why a word can be used to refer to a diversity of things, he creates the terms 'family resemblance', thus indicating that the reason for it is not the presence of some common feature but of a network of overlapping and criss-crossing similarities. He proposes the same kind of analysis for philosophical terms such as 'knowledge', 'proposition', 'memory', 'intention', 'thought', 'rule', 'belief'.