The first task leads upon something of a wild-goose chase. The number of movements which a sonata might contain never became rigidly fixed. A single movement, however, is not a sonata in the generally accepted meaning of the word. It is true that the separate pieces of D. Scarlatti are still called sonatas; but this is only one of the few cases where the original natural use of the word has persisted beside the arbitrarily restricted one. We are, as a matter of fact, almost forced to this continued free use of the term by the lack of a more specific one to cover the circumstance, or even of a suitable abstract one. As we have seen, the few pieces Scarlatti published himself he called _esercizii_. Even in his day the word sonata was applied mostly to compositions made up of two or more movements. His pieces were not fugues; neither were they dances. They were too regular and too compact to be called fantasies or toccatas. They were not rondos, and his imagination was sterile in fanciful titles such as Couperin gave to his pieces. Our modern minds reject his own title as utterly unmusical. In abstract terms we have ‘piece,’ which may do for the historian but not for the program. ‘Movement’ has been chained up in the sonata and symphony. ‘Gems’ and ‘jewels’ are too often in music a paste of musk and tears. So we hold to sonata, for the lack of anything better. Though the word originally signified any music sounded or played on instruments, thus differentiating instrumental music from vocal, its use was limited early in the seventeenth century to music written for groups of strings or wind. At that time, it will be remembered, harpsichord and clavichord music was still essentially organ music, to which the word sonata was rarely applied. The string sonatas had developed chiefly from the old _chanson_, the setting of a poem in stanzas to polyphonic vocal music. The composer attempted in this old form to reflect in his music the varied meaning of the stanzas of his poem. Thus the music, taken from its words and given to groups of strings to play, was more or less clearly divided into varied sections, showing, as it were, the shape or skeleton upon which it had originally been moulded. At first the instrumentalists, even the organists, as we have seen, were content merely to play upon their instruments what had been thus written for voices. Such had long been their custom with popular madrigals and with other simpler forms.