I really enjoy hearing the thoughts of artists dead and gone. People who's concepts and work has changed the way people view the world... so I'll share some I've collected.

Art is not what you see, but what you make others see.
Edger Degas

When I am finishing a picture, I hold some God-made object up to it - a rock, a flower, the branch of a tree or my hand - as a final test. If the painting stands up beside a thing man cannot make, the painting is authentic. If there's a clash between the two, it's bad art.
Mark Chagall

Never permit a dichotomy to rule your life, a dichotomy in which you hate what you do so you can have pleasure in your spare time. Look for a situation in which your work will give you as much happiness as your spare time.
Pablo Picasso

I don't do drugs. I am drugs.
Salvador Dali

Progressive art can assist people to learn not only about the objective forces at work in the society in which they live, but also about the intensely social character of their interior lives. Ultimately, it can propel people toward social emancipation.
Salvador Dali

I feel that there is nothing more truly artistic than to love people.
Vincent Van Gogh

One may have a blazing hearth in one's soul and yet no one ever came to sit by it. Passers-by see only a wisp of smoke from the chimney and continue on their way.
-Vincent Van Gough

Whatever an artist's personal feelings are, as soon as an artist fills a certain area on the canvas or circumscribes it, he becomes historical. He acts from or upon other artists.

-Willem de Kooning

The secret to so many artists living so long is that every painting is a new adventure. So, you see, they're always looking ahead to something new and exciting. The secret is not to look back.
-Norman Rockwell

I always have a good reason for taking something out but I never have one for putting something in. And I don't want to, because that means that the picture is being painted predigested.
-Robert Rauschenberg