Why is it lucky for brides to wear "something old, something new, something borrowed, something blue" or to be carried over the threshold? For answers, check out the "Field Guide to Luck" by Alys R. Yablon.

It's a light and breezy compendium of lucky charms, spells and portents that explains their origins, rituals and cultural contexts. For example, in Japan a "maneki neko" or the calico cat, is considered good luck. So is a house, or office cubicle, with the "beckoning cat" ceramic replica. Want to know about more cat superstitions? Check the referrals "black cat" or "nine lives of cats."

Small household legends are demystified. Why a prohibition against opening an umbrella indoors? Umbrellas, or parasols, originally "were used not to shelter people from rain but to shield them from harsh sunlight," Yablon explains. "It was thought that opening one indoors would insult the sun gods."

The saying "not worth his salt" comes from the Romans, when soldiers were paid in salt instead of coin. So a person "not worth his salt" wasn't much of a trooper.

One of the many pleasures of this small book is a glossary of terms, a subject index and a bibliography that includes many Web sites for future research.

The "Field Guide' might even show you that what you thought was correct, is 100 percent wrong. The term "luck of the Irish," for example, was originally ironic. "The phrase `luck of the Irish' was mainly used sarcastically to explain the many hardships the Irish people have faced over their long complicated history," Yablon says. And leprechauns "were stingy, grouchy creatures who made shoes for fairies and were generally not cute or cuddly much less lucky."

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