The piece
In 1722 Bach gathered preludes and fugues in all twenty-four major and minor keys into The Well-Tempered Clavier, and this prelude opens the first book. The whole piece unfolds a single gesture: one chord per bar, spread out as an arpeggio. This easy version, written for Noctave from the opening and the close of the original, replaces the sixteenths with eighths and keeps only once per bar the figure Bach plays twice.
In the left hand, a bass note falls on the first beat, then a second note enters an eighth later and is held to the end of the bar: press it down without letting go of the first. The right hand waits one beat, then plays three rising notes twice, G–C–E in the first bar. From one bar to the next, some notes often stay put; spot the ones that move before you play. That is the real reading work this prelude asks for, and it prepares you for the full version. The fermatas at the end invite you to let the last chord ring.