Sanguineus und Melancholicus 

What comprises good performance? The ability through singing or playing to make the ear conscious of the true content and effect of the composition. Any passage can be so radically changed by modifying its performance that it will be scarcely recognisable... Good performance, then, occurs when one hears all notes and their embellishments played in correct time with fitting volume produced by a touch which is related to the true content of the piece (Versuch ber die wahre Art das Clavier zu spielen). C.P.E. Bach’s instructions illustrates the aestheticism of the era. In his eyes good performance is a matter of portraying rage, anger, and other passions or the briskness of allegros... the tenderness of adagios. Much of Bach’s music has a strong improvisatory character, with large dynamic ranges, dramatic changes of mood, and sudden textural contrasts (The Empfindsamkeit style). These are the affects that the performer must understand and identify in Bach’s music. One of C.P.E. Bach’s most programmatic chamber pieces is entitled a Conversation between a Sanguineus and a Melancholicus.