The work brings together a collection of previously unpublished essays which offer a systematic account of Wittgenstein's philosophy of mind and contribute in an absolutely new and original way to illuminating his later conception of human perceptive, emotional and cognitive language from both a theoretical and a historical point of view. The focus is on the fundamental categories of philosophical grammar, on the analysis of intentionality, of belief and Moore's paradox, on certainty and doubt, on will, memory, sensations and emotions, as well as on the theory of aspects and private language and the relationship with relativism and psychologism. In the recent literature there are undoubtedly numerous qualified publications dedicated to the themes of philosophical psychology as they emerge from Wittgenstein's Nachlass and from his writings on this subject published in the last decade. This book, however, provides the essential points of reference of Wittgenstein's late treatment of psychological concepts in the context of the general features of his early philosophy of science and language and in the framework of the trends of his time. Audience: Scholars and students, philosophers, linguists, psychologists, sociologists, cognitive scientists, logicians, historians of contemporary philosophy and science.