Philosopher Ludwig Wittgenstein had an enormous influence on twentieth-century philosophy even though only one of his works, the famous Tractatus Logico-Philosophicus, was published in his lifetime. Beyond this publication the impact of his thought was mainly conveyed to a small circle of students through his lectures at Cambridge University. Fortunately, many of his ideas have survived in both the dictations that were subsequently published, and the notes taken by his students, among them Alice Ambrose and the late Margaret Macdonald, from 1932 to 1935. These notes, now edited by Professor Ambrose, are here published, and they shed much light on Wittgenstein's philosophical development. Among the topics considered are the meaning of a word and its relation to common usage, rules of grammar and their relation to fact, the grammar of first person statements, language games, and the nature of philosophy. This volume is indispensable to any serious discussion of Wittgenstein's work.