This is, as from the author of The Concept of Mind it could scarcely fail to be, a bold and rollicking book. It is also one of the most important works about Plato to have appeared since the first volume of Sir Karl Popper's The Open Society. Whereas The Concept of Mind was a general offensive against Cartesian views of man, eschewing any precise references to particular sources, Plato's Progress deals with scholarly questions of datings and developments, showing and demanding familiarity with a wide literature. Yet Professor Ryle is still incapable as ever of the dry-as-dust.