A tabulation of design for first strains of music in various editions of Playford's English Dancing Master (all editions after the first: Dancing Master). The first edition was published in 1651, the seventeenth (and last) in 1728.
What I call "4-bar themes" are similar to Lully's first strains that are really phrases, not themes in Caplin's sense. In Playford's first edition, these 4-bar themes predominate (see the second column in the table). Next in line are the sentence and the antecedent-continuation model, confirmation of the importance of both in 17th century music. In the later editions (see the third column), the obvious change is what we might call the rise of the period and a drop in the number of sentences.
Here is one example of a dance whose music starts with a "4-bar theme": Lady Cullen. "Theme" and "section" are the same, if one takes the repeat sign as a section demarcator, in the same way as in almost all later dances. If we include the repeat, then the resulting eight bars (that is, mm. 1-4 twice) are a period (though an awkward one in which the antecedent closes on the tonic). If we regard the entire piece (mm. 1 to 4 + 5 to 8) as a single theme, then it is antecedent-continuation. If we include all repeats (1 to 4 + 1 to 4 + 5 to 8 + 5 to 8), the result is a compound (16-measure) sentence.
"4-bar theme"; antecedent of an antecedent-continuation; (with repeat) period; presentation unit of a 16-measure sentence. Of course, the actual design of Lady Cullen when used for dancing will be this: if L stands for the music, then LLLLLLLL. . . as many times as needed for all to complete the figures (this is a long dance, where the length of the dance depends on the number of people dancing).
All this reminds us (1) that the formal function depends on the level one is considering; (2) that Caplin's model does have an unfortunate repetition of labels at 8-bar and 16-bar levels; (3) that in 17th century music there is a fluid relationship between phrase, section, and theme.
