Musical forms are clearer and more regular in the Baroque period than in most other historical periods. Two factors that appear to have contributed to this, one of them social, the other intellectual, were mentioned earlier.

The social factor is the patronage system, whereby the court and the church demanded a large amount of music and expected it to be produced in a hurry, almost as soon as it was ordered. Therefore composers needed to rely on formulas that could be applied quickly and efficiently. What is amazing about the church cantatas that Bach wrote every week (at one point in his career) is how imaginatively he varied the standard forms for the various components of a cantata. But it was very helpful — in fact, it was absolutely necessary — for him to have those standard forms in place as a point of departure.

The other factor is the scientific spirit of the age, which affected composers only indirectly, but affected them nonetheless. One can detect the composer’s ambition to map the whole range of a piece of music and to fill it in systematically in an orderly, logical, quasi-scientific way. This ambition seems to have been based on the conviction that musical time could be encompassed and controlled at will, an attitude similar to that of scientists, philosophers, and craftsmen of the age.

The music of Bach, in particular, shows this tendency on various levels. Look, for example, at the symmetrical arrangement of the seven sections of his Cantata No. 4, diagrammed on page 148. The last fugue in his Art of Fugue, a composite work containing twenty items, is a more famous example. An ordinary fugue, as we shall see, is a polyphonic composition that deals exclusively with a single theme. This fugue deals with four themes, one after another, in four sections; then in the last section all four themes combine in four-part counterpoint. Theme No. 4 spells “Bach” in a musical code! Even Bach’s shortest compositions can have schematic features, as we will see on page 129.