The Institut des Hautes Études Scientifiques in France is an institute of advanced research in mathematics and theoretical physics. This book contains snapshots of its scientists and visitors in lecture halls, chalk or pencil in hand, engrossed in dialogues. Every one of them contributed a little essay on subjects from mathematics to philosophy. Altogether in the book, there are snapshots of fifty people. There are photographs of M. Atiyah, Y. Choquet-Bruhat, J.-P. Bourguignon, A. Connes, P. Cartier, P. Deligne, J. Fröhlich, M. Gromov, V. Kac, M. Kontsevitvh, D. Sullivan and J. Tits, to mention just a few. The book reflects the enthusiasm of mathematicians and scientists and can serve as a recreational read for anyone.