"Ars longa, vita brevis"
When I was a student in college, my roommate and I spray painted that on the wall of our apartment. In English it means art is long, life is short, and was coined by Hippocrates, the father of medicine.
It's actually part of a longer text which, when rendered in English, means "Life is short, the art of medicine is long, opportunities are fleeting, experiment is dangerous, and judgement is difficult." It is Hippocrates call for all physicians to know well their craft, for at any moment they may be called to make split second decisions to save a life. That's why it is ever the physician's duty to continue to learn and practice.
Why a physician's aphorism is my art philosophy is simple. First, it sounds cool. Second, it tells me that learning one's craft is a process that only ends with one's death. Art is something that takes a lifetime to learn, so can you ever really master art?
Therefore, as an artist, you are always the student.
Which is to say, never stop learning.
Never stop creating.