As the busiest and most important musician in one of the most active musical centers in Germany in the 1730s and ’40s, how did Bach find time to meet all of his obligations? He was serving as director of church music in Leipzig with all the myriad duties that entailed, and he directed the Collegium Musicum, which presented weekly concerts. (For more about the Collegium see the notes for his Double Violin Concerto.)

Like many an enterprising composer before and after him, Bach borrowed from materials he had composed earlier to meet the constant demand. For his keyboard concertos he drew on preexisting violin concertos, cantata movements, and harpsichord and organ pieces. Instead of being frowned upon, such borrowing was considered a practical and artful way of providing a great amount of music. He also tapped concertos by other composers, notably Vivaldi, adopting his three-movement model—fast, slow, fast—together with his ritornello form (in which a refrain alternates with episodic excursions).

Was Bach aware that he was creating an entirely new genre with his keyboard concertos? His older sons carried the concept to other German centers, and, though too young to have participated in the Collegium concerts, his son Johann Christian brought the genre to London. Mozart, often considered the father of the modern piano concerto, was profoundly influenced by the keyboard concertos of the “London Bach,” whom he greatly admired.

Probably the best known of Bach’s keyboard concertos, the D minor Concerto borrowed its first and second movements from Cantata 146: “Wir müssen durch viel Trübsal” (1726–28); the third movement had also been employed as the sinfonia of Cantata 188: “Ich habe meine Zuversicht” (c. 1728). The cantata movements in turn had probably been transcribed from a violin concerto that no longer exists, but which has been reconstructed.

The D minor Concerto presents an earnest and dark-hued world. The Allegro opens with a driven theme, played by soloist and tutti (ensemble) strings in unison and octaves, which returns in a developmental episode and then closes with the theme’s final statement in the original key, again in unison and octaves.

Bach’s use of a minor key (G minor) for the slow movement further emphasizes the Concerto’s dark color—in his other minor-mode concertos and sonatas the slow movement is usually in a major key. The Adagio is structured on a repeating pattern in the bass (basso ostinato or ground bass) of thirteen measures, which is played in unison and octaves at the opening and again at the close of the movement. The soloist plays a poignant cantilena (lyrical melody) over the intervening presentations of the ground bass. Short passages are introduced between patterns for the purposes of changing from one key to another.

A driving rhythmic motive launches and pervades the closing movement. Brief respite from the prevailing relentless quality comes in the form of a cadenza (improvisatory passage for the soloist alone) just before the final statement of the main theme. Bach is said to have liked a very brisk tempo for such movements.

© Jane Vial Jaffe