What is finish? A picture is finished when all traces of work, and of the means employed to bring about the result, have disappeared.
In the case of handicraftsmen - the weaver, the potter, the smith - on their work are the traces of their hand. But it is not so with the painter; it is not so with the artist.
Art should have no sentiment about it but its beauty, no technique except what you cannot observe. One should be able to say of a picture not that it is 'well painted,' but that it is 'not painted.'
What is the difference between absolutely decorative art and a painting? Decorative art emphasises its material: imaginative art annihilates it. Tapestry shows its threads as part of its beauty: a picture annihilates its canvas: it shows nothing of it. Porcelain emphasises its glaze: water-colours reject the paper.
A picture has no meaning but its beauty, no message but its joy. That is the first truth about art that you must never lose sight of. A picture is a purely decorative thing.