In all these arts many differences of opinion exist among masters as to the methods and forms which should be authoritative; and in so far as such is the case, the individual must be allowed to make many apparently arbitrary personal choices.

The fact that a man has such choices to make is the circumstance which most clearly distinguishes the practice of an art from that of a science, but this circumstance, instead of being an excuse for technical irresponsibility or mere eclecticism, should, on the contrary, stimulate the individual more completely to justify his choice.

In his work he is fighting the battle not merely of his own personal career, but of a method, of a style, of an idea, or of an ideal.

The practice of the several arts need not suffer from diversity of standard, provided the several separate standards are themselves incorruptible.

In all the arts--and by the arts I mean all disinterested and liberal practical occupations--the difficulty is not that sufficiently authoritative standards do not exist, but that they are not applied.