Mark Hambourg on practice:
In regard to practice I do not think it wise for the aspiring pianist to spend such a great amount of time at the piano. Four hours of concentrated work daily seems to me sufficient. Of course it is the quality of practice that counts. The old saying, 'Practice makes perfect,' does not mean constant repetition merely, but constant thinking and listening. I advise students to stop after playing a passage several times, and think over what the notes mean. This pause will rest ears and hands; in a few moments work can be resumed with fresh vigor.
Ethel Leginska on teaching:
In teaching the piano, as you know, every pupil is different; each has his or her own peculiar hand, and a different degree of intelligence. So each pupil must be treated differently. This is really an advantage to the teacher; for it would be very monotonous if all pupils were alike.