English to French Art/Literary Other

Hello there,

I would need some help with this sentence. Not sure I understand the idea behind it. Could you help? Here's an extract of the text:

This is Edward Hopper's lesson to the painters of our time and to anyone else interested enough to learn from him. He had the courage to sit down and open himself to reality, to respond freely to it without the protective, stultifying psychic armor of theories and preconceived formulas of seeing. He was uncluttered by the passing aesthetics of the day.

Many thanks!