Piano players in some ways have it easier than other musicians. For instance, a pianist, if called upon to play a perfect A, presses a button on the instrument, and out comes a perfect A (if the piano tuner has done his job right). Violinists, slide trombonists, and even singers run the risk of sliding around and being too low or too high. But I was surprised to find that there is controversy in such things as how a piano ought to be tuned, or how scales are to be divided. I am not a musician, but in _How Equal Temperament Ruined Harmony (and Why You Should Care)_ (Norton), Ross W. Duffin asserts that even classically trained musicians are not aware that there is more than one way to divide scales, and he also asserts that the current predominant system, Equal Temperament (ET), is not necessarily the best for all purposes. "It's all wrapped up in recent evolutions in musical performance and teaching, the result of decades of delusion, convenience, ignorance, conditioning, and oblivion." Musicians are going to get much more out of this book than I did; Duffin says, "It's for everyone who performs or cares about music," but many of the technical aspects of his argument were often above the head of this "carer". Nonetheless, this is an important book to give, again, the vital lesson that much of what we take for granted, much of what we consider fundamental, is only the result of the past's convenient compromises.
The difficulty with dividing up the scale is one of physics and aesthetics. Scales divided into octaves don't quite contain perfectly the fifths (Duffin explains all this) and one solution is to narrow (in musical terms, to "temper") each of the twelve fifths by one twelfth of the missing fit. That is an equal temperament (ET). Even Duffin agrees that equal temperament is an elegant solution to the problem, but like all solutions to complicated problems, it has disadvantages, especially that it makes major thirds dissonant. Musicians originally were not ready to tolerate such harsh major thirds, and so irregular (non-equal) temperaments were preferentially used until the nineteenth century, and Duffin makes the case that even into the twentieth century equal temperament was not the enforced standard it has come to be. In the twentieth century, however, there were many social forces to make temperaments equal. The piano became a central piece of furniture for homes of all classes, and the piano (and to a lesser extent, the organ) became the main instrument that other instruments had to play around. With music instruction becoming more popular, makers of those other instruments found it simpler to make them based on the basic equal temperament system.
Duffin writes that equal temperament has been so thoroughly adopted "... that most musicians today are not even aware that any other systems exist, or that if they exist, that they have any musical worth whatsoever." The biggest drawback in such ignorance is that pre-equal-temperament compositions, of course, have to be fitted onto equal temperament instruments and playing. The enthusiasm for historically accurate performances, even with historic instruments, can never be fully successful without accepting that the composers and players of the time were using historic temperaments rather than the current monolith. "I'm not saying that harmonic intonation should replace ET entirely and substitute its own tyranny," says Duffin, "only that ET is not necessarily the best temperament for every single musical situation encountered by today's musicians." Duffin's book is scattered with sidebar pages to introduce concepts like temperament itself or pure intervals, and also to give accessible capsule biographies of musicians, composers, and music theorists who have taken part in the history of temperaments. One of the musicians so profiled is the cellist Pablo Casals, with whose words Duffin gleefully winds up a mind-stretching work: "Do not be afraid to be out of tune with the piano. It is the piano that is out of tune. The piano with its tempered scale is a compromise in intonation."
