This book presents two lost histories. One relates to the biography of the Vienna Circlephilosopher Otto Neurath 18821945 whose lifestory reflects the tumultuous early twentieth century the other to the history of museums exhibitions and of audience advocacy. A polymath Neurath united theory and practice in many fields from history and philosophy of science to adult education. Until now the practical application of Neuraths philosophical convictions his innovations in museology have not been presented coherently. Neuraths museum and exhibition work in the Red Vienna 19251934 and later in the Netherlands and in the UK had a specific educational mission and a clear commitment to its users shaped by egalitarian notions and meant to promote social development. Nowadays museums are searching for ways to connect more closely with their audiences. The ideas and methods of Otto Neurath his unusual approach to museums the emphasis on communication and learning can be better assessed with this book. It will be of great interest to those concerned with museums and exhibitions as spaces for education and communication.