I do think that a good pictorial idea is worth more than a lot of manual dexterity. - Frank Stella

Clement Greenberg talked about the ideas or possibilities of painting in his - I think -, 'After Abstract Expressionism' article, and he allows a blank canvas to be an idea for a painting. It might not be a good idea, but it's certainly valid. Yves Klein did the empty gallery. He sold 'air', and that was a conceptualized art, I guess.

If you don't know what Ad Reinhardt's) paintings are about, you don't know what painting is about.

Only what can be seen there [in the painting] is there.. .What you see is what you see.