The A minor sonata is the first of only two Mozart piano sonatas in a minor key (the other being No. 14 in C minor, K. 457). It was written in one of the most tragic times of his life: his mother had just died, and his father blamed him for his wife's death. Mozart was devastated, and poured his constant torment into his sonata, one of the darkest. The last movement in particular has an obsessive, haunted quality about it, heightened near the end by the interruption of the relentless drive to the conclusion by repeated and chilling quiet falling passages.