A curious trait characteristic of Purcellian literature is that his sonatas are usually discussed alongside the fantazias. Howard noted that the supposed chronology— the fantazias were composed before the sonatas—dictates the order in which these genres are discussed in the literature, and only rarely do commentators refer to the sonatas before their survey of Purcell's achievements in the field of fantazia.

Just as in Tilmouth's article on the sonatas, where the author could not avoid at least some mention of the fantazias and their contrapuntal technique, so will the present study discuss other genres from time to time. I will refer to the fantazias more than to other genres, as it will be argued that an essential palindromic technique that appears in the sonatas (commutatio; see chapter 6) originates in the fantazias. In such cases, the fantazias provide the most enlightening comparison with the sonatas.

That which is shared and that which is different between Purcell's sonatas and fantazias has preoccupied many of the commentators on Purcell's music, and a joint discussion of the two genres seems natural because of their chronological proximity. To quote but two commentators, Franklin B. Zimmerman argues that “comparing [the sonatas] to the fantasias in their stylistic and formal development, one sees that they are part of an unbroken stylistic continuum”; Bruce Wood calls the sonatas “direct descendants” of the fantazias. Even writers who argue for greater distinction between the genres seem to agree that, at the very least, the canzona movements that feature in most of the sonatas are indebted to a similar mode of polyphonic thinking represented in the fantazias.

The fact that Purcell himself bound the two genres together (even literally) also encourages a joint discussion. It is possible that he sent several empty gatherings to be bound together with gatherings already containing the fantazias and three (or four) sonatas, thus creating the bound autograph known today as 30930 (albeit with a different page order). In addition, Purcell's fantazias and sonatas are equally original within their respective genres.

When editing the fantazias or sonatas, the joint study of Purcell's contribution to the two genres may enrich one's editorial policy and inform one's editorial decisions.