"The ancient sources are elusive passages in esoteric books the ordinary student never encounters, and secondary treatments are fragmentary and recondite. Professor Jonas’s synoptic book, well organized and beautifully written, is therefore a pioneer effort, unrivaled and indispensable. It is at once a work of original scholarship by an acknowledged authority in its field, and so lucid in its presentation that the enormous learning which it exploits is never obtrusive. It is a feat of imaginative scholarship to combine scattered and tangled threads into a unified texture with patterns clearly revealed in their dark side and in their light, and it is no less a feat to clarify the strange patterns by relating them to more familiar ones."