Here is Bach's own introduction to the Inventions and Sinfonias: Forthright instruction, wherewith lovers of the clavier, especially those desirous of learning, are shown in a clear way not only to learn to play two voices clearly, but also after further progress to deal correctly and well with three obbligato parts, moreover at the same time to obtain not only good ideas, but also to carry them out well, but most of all to achieve a cantabile style of playing, and thereby to acquire a strong foretaste of composition.