Do you know how the custom of the handshake began? Do you know what the Irish believed dimples said about a person's inner good and evil? Are you aware what will happen to little girls who whistle? Would you have guessed that the African Zulus and some Native American tribes shared a strong disdain for mothers-in-law?

That's just a tiny taste of the answers which await you in Knock on Wood, Carole Potter's "encyclopedia of talismans, charms, superstitions and symbols."

The book is a clever collection of superstitious bits and pieces from all over the world. It's a handy resource if you suddenly question what a habitual action means, like tossing a pinch of spilled salt over your shoulder or crossing your fingers for luck. It's also a fun way to spend a lazy hour or two, browsing and learning the origins of numerous common idiosyncracies of modern society.

What should you do when moving into a new home? What should you never do in a theater? (Besides shouting "FIRE," that is.) Where did our Easter traditions come from? What's a good aphrodisiac? And who is St. Swithin? It's all in there.

The appendix at the end includes a variety of handy information, like lists of birthstones, the meanings of colors, flowers, edible plants, herbs and trees, standard holidays, sports superstitions, traditional anniversary gifts and other interesting stuff.

A few entries seem out of place, as if Potter was stretching to pad it out by a few more pages. For instance, there's a biographical entry on the real Johnny Appleseed. He's certainly not a talisman, charm or superstition, although I suppose a case could be made for listing him as a symbol. Anyway, it's a small matter; I'm quite sure almost anyone picking up a copy of this book will be found soon after idly turning the pages, absorbed by the tidbits within.

Knock on Wood is both entertaining and useful. Make room for a copy on your bookshelf -- and make sure it's in a spot you can reach easily and often.

[ by Tom Knapp ]