Andrew Loomis said this quote

As a student I thought there was a formula of some kind that I would get hold of somewhere, and thereby become and artist. There is a formula, but it has not been in books. It is really plain old courage, standing on one's own feet, and forever seeking enlightenment; courage to develop your way, but learning from the other fellow; experimentation with your own ideas, observing for yourself, a rigid discipline of doing over that which you can improve.