In the spirit of Voltaire—and occasionally in the spirit of P. G. Wodehouse—P. B. and J. S. Medawar have crafted for the life sciences a source of reference that is meant for browsing, a book both authoritative and filled with delights. The authors’ breadth of knowledge is encyclopedic— arranged, appropriately enough, from A to Z—but more than that, they illuminate the ideas of biology with wit and intelligence and uncommon good sense. They bridge the chasm in our culture between the technically and the humanistically trained, breaking the code of jargon that limits access to scientific understanding. The Medawars’ special gift is to offer, at the same time, a pleasurable introduction for the layman and a source of new insight for the specialist.

In this book we can find a clear and meaningful definition of interferon, a useful explanation of the immune system, and thoughtful essays on sociobiology, eugenics, and aging. But we also find: “It is a popular fallacy that chewing gum regains its flavor if removed from the mouth and parked, say, under a chair.”

Whether in a serious discussion of cancer or a whimsical reflection on “chicken and egg” imagery in science, the Medawars’ blend of fact, literary allusion, historical anecdote, mythical and folk tradition, and even professional gossip is a rewarding exercise in biology as a humanistic endeavor.