Urtext Edition of Mozart's Piano Sonata No. 7 in A minor K.310 (300d). Edited by Ernst Herttrich with fingerings by Hans-Martin Theopold. This A minor Sonata suddenly opens a new world. Einstein may well have been right in assuming that the Sonata was written under the weight of MozartÂ’sgrief at his motherÂ’s death in Paris.