Maurice Denis said this “A picture--before it is a a war horse, a female nude, or some anecdote, is essentially a flat surface covered with colors in a particular order.”Does the word "flat" have different meanings. I understand the first use of the word ("essentially a flat surface"), but I'm not sure I follow its usage through the rest of it.He’s made the lady flatter and bolder
more modern and flattened style of realism
And one says he would paint her flatly, as if in real light,
Other than the obvious, what does "flat" mean?
He may be referring to how the lighting is idealized in the earlier works. Single source light, such as direct sun, flattens the shadows. To model a subject, multiple sources of light will backfill and bring definition. Usually, this is a "key light" of reflected light, coming from the side and rear.
Flat means without modeling, which is a fancy word for shading. So instead of making figures round, as did Titian and Giorgione, they are stressing a 2-dm flatness, like a plane in geometry.
This flatness, and a new kind of space through warm and cool colors and the tension and movement thereof, is what concerns much of modern art. More about this in upcoming "lectures."