Corner any Stanford pupil you like, and ask him to confess the sins he most hated being discovered in by his master. He will tell you ‘slovenliness’ and ‘vulgarity’. When these went into the teacher's room they came out, badly damaged. Against compromise with dubious material or workmanship Stanford stubbornly set his face.
None of us lived in the easy atmosphere of neutrality when we took lessons with him. Mastery of subject carried with it, in him, a very definite sense of where he stood; and that definition ill accorded with vagueness of attitude in others. By methods in which long practice taught him to believe he brought his pupils themselves to know where, and for what, they stood. Whatever else one might have become under his shrewd guidance, it never could have been a wobbler, a neutral, a befogged practitioner. It was often his way to make a student fight hard in defence of a point of view, an expression, or a mere chord. Failure in this was apt to bring trouble upon the pupil. But that the defence generally prevailed, and brought self-reliance-as Stanford, in his wisdom, always hoped it would or ought to be clear to anyone who observes the remarkable degree to which most of his pupils have established their own particular identities in composition.
Howells, Herbert, Music & Letters, vol. 5 no.3 (July 1924) p. 199 [minor edits]