This publication publishes lectures and notes by Ludwig Wittgenstein, which were preliminary materials for his Philosophical Investigations, one of the main philosophical works of the 20th century. The Blue Book is a summary of lectures Wittgenstein gave to students at Cambridge in 1933-34. The Brown Book was also dictated by the philosopher to his Cambridge students. It is here that Wittgenstein attempts, in a popular form, to talk about the key themes of his later philosophy, and also gives a detailed list and analysis of language games (he will not go into them in such detail in the future). The Blue and Brown Books, classic texts of the late Wittgenstein , give us the opportunity to plunge into an unusual philosophical “stream of consciousness” and learn first-hand about the thoughts of a man who radically changed the course of modern philosophy.