§ 19. The degree in which the ground colors are extended over his picture, as he works, is to a great painter absolutely indifferent. It is all the same to him whether he grounds a head, and finishes it at once to the shoulders, leaving all round it white; or whether he grounds the whole picture. His harmony, paint as he will, never can be complete till the last touch is given; so long as it remains incomplete, he does not care how little of it is suggested, or how many notes are missing. All is wrong till all is right; and he must be able to bear the all-wrongness till his work is done, or he cannot paint at all. His mode of treatment will, therefore, depend on the nature of his subject; as is beautifully shown in the water-color sketches by Turner in the National Gallery. His general system was to complete inch by inch; leaving the paper quite white all round, especially if the work was to be delicate. The most exquisite drawings left unfinished in the collection--those at Rome and Naples--are thus outlined accurately on pure white paper, begun in the middle of the sheet, and worked out to the side, finishing as he proceeds. If, however, any united effect of light or color is to embrace a large part of the subject, he will lay it in with a broad wash over the whole paper at once; then paint into it using it as a ground, and modifying it in the pure Venetian manner. His oil pictures were laid roughly with ground colors, and painted into with such rapid skill, that the artists who used to see him finishing at the Academy sometimes suspected him of having the picture finished underneath the colors he showed, and removing, instead of adding, as they watched. § 20. But, whatever the means used may be, the certainty and directness of them imply absolute grasp of the whole subject, and without this grasp there is no good painting. This, finally, let me declare, without qualification--that partial conception is no conception. The whole picture must be imagined, or none of it is. And this grasp of the whole implies very strange and sublime qualities of mind. It is not possible, unless the feelings are completely under control; the least excitement or passion will disturb the measured equity of power; a painter needs to be as cool as a general; and as little moved or subdued by his sense of pleasure, as a soldier by the sense of pain. Nothing good can be done without intense feeling; but it must be feeling so crushed, that the work is set about with mechanical steadiness, absolutely untroubled, as a surgeon,--not without pity, but conquering it and putting it aside--begins an operation. Until the feelings can give strength enough to the will to enable it to conquer them, they are not strong enough. If you cannot leave your picture at any moment;--cannot turn from it and go on with another, while the color is drying;--cannot work at any part of it you choose with equal contentment--you have not firm enough grasp of it.