A pair of author-naturalists with their eyes open to the parallels and peculiarities, physical and habitual, of the mating cycle's grand design write with wit and true biological insight that make their book entertaining and informative. Within chapters on different stages there is an easy shift in reference to all kinds of animals so that the aspects of the instinct come into focus with amazing clarity. Gently done, we think this kind of book is a fine help with both physical and social aspects of reproduction.