Salvador Dali says

If you understand your painting beforehand, you might as well not paint it.

Modern painters having almost totally lost the technical tradition of the ancients, we can no longer do what we want to do. We only do “whatever comes out of us.” There is a Spanish proverb which defines the common people's reaction to a bad painter: “If it comes out with a beard, it will be Saint Anthony, and if it comes out without a beard it will be the Immaculate Conception.”  

And what is a painting? It is a piece of canvas or of wood on which has been spread with art a little earth mixed with a little oil, by the aid of a few hairs attached to the end of a stick!

It would therefore be prudent to assume that in order, with such simple means, to spread paint on a piece of wood and to create a work appealing to the senses which will remain immortal, it must be necessary to proceed and to manipulate it with a kind of art close to magic, and that in any case the simple technique of house painters will not suffice. In point of fact, to limit ourselves for the moment to the medium, it must be clearly understood that the paint as it comes from the tube is nothing more than that which is used to paint doors; but that nevertheless, when knowingly used, it becomes, as it became for all the great ancient masters, a matter more precious and inimitable than all the enamels and all the gems of creation…. I should like to recommend to … every young apprentice in painting that he gaze long and philosophically one afternoon in spring at the azure of the sky, on a day wholly without clouds and preferably in a Mediterranean country. Then he will observe that this azure is composed, as it were, of a precious substance which eludes his rational faculties, for at the same time that it will appear to him to be made up of an infinitely smooth and hard substance, like an agate sphere, this homogeneity, so opaque and materially corporeal, will seem luminous and as if composed of transparency and of spirituality itself. And in this the sensations just described will be in accord with physics, since the hardness and the violence, so to speak, of such an azure are constituted of nothing but infinite layers of superposed transparent air. Exactly the same thing is true of a beautiful pictorial matter. A color as it comes from a tube does not exist as a beautiful and transcendant pictorial matter. The latter, on the contrary, is constituted and formed, like the very azure of the sky which serves as our example, by a succession of subtle, quasi-spiritual and infinitely fine successive layers, as transparent as possible, and for the obtaining of which the magic of media intervenes; those mysteriously blended films … superposed, spread one over the other according to the harmony of their physical and chemical properties, attaining the maximum of brilliancy, more limpid than that of enamel and less fixed, since it is susceptible to all the future mysteries and aureolations of patina. And we shall have to be particularly attentive to this decisive subject of “matter,” since it is by this specifically sensorial means that we shall be made aware of the most finely shaded ideas in the realm of the senses, and since nothing in the realm of visual sensuality is so capable of beauty, of nobility and of honor or, on the other hand, of ugliness, of ignominy and of degradation, depending on the manner in which this celestial or foul matter is used and manipulated.