The Sonata in A major, K. 331, is one of the most well known works of Mozart. I remember practicing it endlessly when I was a child - at the time, I think I was playing Mozart better than I do now... In order to play Mozart [well, that is], a certain degree of innocence, spiritual "cleanliness", and purity, is required... Here are Einstein's thoughts on this sublime work:
"Next comes the sonata in A major (K. 331), which has become a favourite - the one with the variations at the beginning, the Rondo all turca at the end, and the minuet (or rather Tempo di minuetto) in the middle - the work that has given so many people their first impression of Mozart. It is, however, not typical but exceptional; it is in a way a counterpart to the Munich Durnitz Sonana in D, but it places the variations at the beginning, and accordingly casts them in briefer and less virtuoso forms; and it ends with a true scene de ballet. [...] Throughout the work one finds the fullness and sensuous beauty of the Durnitz Sonata, raised to a higher power, just as A major is an intensification of D major. And the minor of the Rondo all turca does not fail to produce a subsidiary effect of mystery".
Here is the 2nd movement of this Sonata - the menuetto - played by Jeno Jandó.