Alone almost of all instruments, the piano represents a kind of abstraction; it is an impersonal and veritable machine for producing sound, complaisant to all touches, seeming to require only a lever set in motion to create an effect. In other instruments, their function itself defines their nature. They have an intrinsic life of their own which even the merest beginner must somehow evoke. This fundamental nature of an instrument determines ultimately its aesthetic. The demands which the more comprehensive aesthetic of the composer impose on the instrument may force an extension of its capacities but can never nullify them. And so a composer learning to instrumentate can do no better than to acquire at the hands of a practising musician an exposition of the instrument's capacities. A masterful score will liven his imaginative use of them, just as a poet's mastery of diction will freshen one's sense of words. The vocabulary, however, is given.