Domenico Scarlatti does not belong. Whether we ask to whom, to where, or to what he belongs, and even if we ask the questions with the slight diffidence proper to any such form of historical enquiry, no comfortable answers can be constructed. The only category into which we may place the composer with any confidence, one especially reserved for such misfits, is that of the Interesting Historical Figure. Thus, although the significance of the composer's work, certainly in the realm of the keyboard sonata, is generally agreed, just how it is significant is yet to be happily established. Most treatments of composers and their music may be divided into two categories, depending on where they locate the composer's image – the rationale for the treatment is either one of reinforcement or one of special pleading, according to whether the composer lies within or beyond the canon. The normal way of arguing a case for the inclusion of music that lies outside the canon is to demonstrate its relevance to or influence on music that lies on the inside. Until the music or the composer concerned have crossed the threshold, this is effectively the only mode of treatment possible.

This may seem far too simple an equation, but one only need bear in mind the difficulty that has always been apparent in treating musical works of art on their intrinsic merits, as it were.