n shows, as it were, a struggle between
two ideals. One was _kinship_, _i.e._ the endeavour to present the
secondary matter in strong relationship to the opening one (the
opening notes or bars of a real second subject were, indeed,
frequently the same, allowance being made, of course, for difference
of key); the other was _contrast_, _i.e._ the endeavour to obtain
variety. Haydn was more affected by the first; Mozart by the second.
In Beethoven the two are happily combined. It is important to notice
the closing bars of many first sections of the period of which we are
speaking. For instance, in E. Bach, the first movement of the sonata
in each of the Collections of 1781 and 1783 has a concluding theme
(as in the sonata of Scarlatti, and frequently evolved from the
opening theme). Though in the complementary key, it cannot count as
"the second subject." It appears after the complementary key has been
ushered in by one cadence, and after having apparently run its course,
it has been wound up by another. Then, again, the portion between the
cadences just mentioned is at times filled with a true theme, so that
the concluding one, like the cave of Abraham's field of Machpelah, is
in reality an appendency. _Sometimes there are several_: the
enlargement of the exposition section by Beethoven, and still more
modern composers, so that it contains sometimes three, and even more
themes, is practically an exposition section on Scarlatti lines, only
on a larger scale: the figure has become a phrase, mere connecting
passages have acquired organic meaning. The second section of
Scarlatti's movement in binary form contained a few bars of
development and modulation. Then a return was made to the opening key
of the piece, _but never to the opening theme_; and in that key a
portion more or less great, more or less varied, according to
circumstances, was repeated. That return to the opening theme is, as
we have already said, the landmark which divides binary from sonata
form.

In sonatas of the middle of the eighteenth century the modulation
section (in a major key) ended in various ways,--on the dominant
chord (of the principal key), on the tonic chord of the relative
minor, the under-dominant, or even on the tonic itself of the
principal key. Later on, Haydn and Mozart kept, for the most part, to
the dominant chord. Beethoven, on account of the distant, and often
abrupt, modulations of his middle sections, generally marked the
approach