No. 1 is Agitato, in B minor, 2/2 time.

Beginning majestically and powerfully, with numerous leaps and utilizing a wide range from low to high registers, this piece intensely stirs emotions, as evidenced by the anecdote that Brahms's friends, upon hearing it, called it 'the young Johannes soaring through the heavens.' Contrasting with this, a smooth, monophonic theme played in pianissimo also appears. In the middle section, where the intensity suddenly fades, it modulates to the parallel major, B major. Here, quiet movements with fewer leaps become central, and against the left-hand accompaniment, the right hand carries two long, sustained melodies. It reaches the tonic chord of B major as if to end peacefully, but immediately after, it shifts to the tonic chord of B minor, with the third lowered by a semitone, and the opening theme returns intensely. After building up to a climax with a fierce, cascading momentum, it quietly moves towards its conclusion.