Pay No Attention to What You Have Learned

In The Rest is Noise, Ross mentions (p. 182) the following "placard-like notice" appearing in the preface to the Ragtime movement of Paul Hindemith's Suite ‘1922’:

Mode d'emploi – Direction for Use!!

Pay no attention to what you have learned in your piano lessons.
Do not consider for long whether you should play D# with the fourth or sixth finger.
Play this piece very ferociously, but keep strictly in rhythm like a machine.
Regard the piano here as an interesting kind of percussion instrument and treat it accordingly.

(This translation from Glenn Watkins, Soundings: Music in the Twentieth Century, Schirmer, New York, 1988, p. 289. Cited by Avior Byron, Schoenberg as Performer: An Aesthetics in Practice, PhD Thesis, Royal Holloway, University of London, London, p. 64). Now, Charles Bukowski was born in Germany and voraciously consumed classical music, so the title of his Play the Piano is almost certainly a nod to Hindemith:

These days there are lots of interesting things being done to pianos, and I'm glad to be getting back into New York early enough to hear this: