Simplicity is the final achievement. After one has conquered all the difficulties, after one has played a vast quantity of notes and more notes, it is simplicity that emerges in all its charm as the crowning reward of art. Whoever wants to obtain this immediately will never achieve it: you can’t begin with the end. One has to have studied a lot, tremendously, to reach this goal; it’s no easy matter.

[La dernière chose c’est la simplicité. Après avoir épuisé toutes les difficultés, après avoir joué une immense quantité de notes, et de notes, c’est la simplicité qui sort avec tout son charme, comme le dernier sceau de l’art. Quiconque veut arriver de suite à cela n’y parviendra jamais, on ne peut commencer par la fin. II faut avoir étudié beaucoup, mème immensement pour atteindre ce but, ce n’est pas une chose facile.]

Frederic Chopin
Frédéric Chopin (1810-1849) Polish composer and pianist
In the diary of Friederike Streicher (née Müller) (1840-04-21)
    (Source)

When told by Müller that what impressed her most about Franz Liszt's playing was his "calmness in overcoming the greatest technical difficulties." Müller was a premiere student of Chopin, 1839-41. Excerpts from her diary are printed in Frederick Niecks, Frederick Chopin: As A Man and Musician, Vol. 2, Appendix 3 (1888).