Before he did all those lovely line drawings, Matisse would make really detailed charcoal drawings and tear them up. He wouldn't leave them about, he thought of them as working drawings. I understand what he was doing: discovering what's there. And then when you come to use line, if you know what you're looking at, it's much easier to make the line meaningful, to find a linear solution to what you want to depict.

From a series of interviews with Marco Livingstone (April 22 - May 7, 1980 and July 6 - 7, 1980) quoted in Livingstone's David Hockney (1981), p. 185