Involving mathematics, philosophy, aesthetics, religion, politics, and physics, Stuart Isacoff 's Temperament invokes the tone of a James Burke documentary. However, the focus is not on a modern invention, but rather a modern convention: that of tuning keyboards so that every key is equally in tune--and equally out of tune. With the existing literature tending to bog down in mathematical theory or historical tuning methods, Isacoff bravely attempts to make this seemingly arcane topic interesting to the general reader. He distills the mathematics and music theory into their simplest essences, and draws apt analogies from the everyday. He also generously peppers the text with the quirks and escapades of its more flamboyant central characters; the relevance of the information is often tenuous at best, but Isacoff has obviously done his homework, and he can be forgiven some frivolity. Less forgivable is his neglect of "well-temperament." Namesake of Bach's masterful collection of 24 pieces (one each in all the major and minor keys), the well-tempered keyboard liberated composers from the howl of badly tuned keys in the way equal temperament did, while preserving the distinct quality of each key. It was a pragmatic and aesthetically rich solution that captivated composers and theorists for decades. Yet Isacoff reserves less than two pages for its description. (Perhaps he deliberately overlooked the topic since it doesn't fit well with his casting of equal temperament's opponents as rigid, dogmatic, and impractical.) Despite its flaws, Temperament is an accessible guide to a fascinating topic seldom discussed outside musical circles. Though the book may not invigorate hard-core theorists, the amateur musician, armchair scientist, history buff, or plain old curious can glean plenty from it. The advent of digital keyboards--some of which can be tuned to historical temperaments at the flip of a switch--makes this an ideal time for the topic to be rejuvenated.