[cloogshicer]

Oh, you might be right.

I downloaded the book a long time ago as a PDF from somewhere. It also included this sentence and it stuck out to me because it was so weird. The rest of the tone of the book felt in the same style to me so I never second guessed it, but you might be correct.

[mkl]

Probably from the canonical site, http://www.pianopractice.org/, where a more up to date edition is available for free. The second edition (that the submission link is based on) does contain that sentence, so it is from the original author. The third edition does not.

[jacquesm]

He isn't, that is exactly what the book says.