I have heard him [Anton Rubinstein] transpose one of the most heart-breaking fugues (heart-breaking, of course, only from a mechanical point of view) of the "forty-eight" from a flat key into a sharp key, the latter not even being one of his own selection, but chosen by a fellow-pianist whom I shrewdly suspected at the time to be guilty of intending to set Rubinstein an impossible task. He played the fugue in question— which I had only too good reason to know by heart — without missing a note or omitting an emphasis. When it was over, I noticed that the perspiration was standing out in great beads upon his massive forehead, from which unwonted symptom of fatigue I drew the inference that he had put a heavy strain upon his powers. But that he had performed this astonishing feat at unforseen request and without a minutes hesitation.