On Velazquez’ Dithering

by F.

The National Gallery in London is currently showing a number of Velazquez’ works. In reviewing the show, the The Economist‘s art writer says that Velazquez knew

…that the very ambiguity of his pictures would encourage the viewers’ imagination and hold their gaze. With opulent colour and form, his brushstrokes entice you into believing his paintings are so real that you cannot look away. Yet when the viewer moves closer to see how he did it, the image evaporates into a blur of paint.

Indeed. An engaging picture lets the viewer complete it. This quality is sometimes called “painterliness.” But an even better description is that such paintings “dither.” Here’s how Harold Speed describes this quality in his early 20th century book The Practice and Science of Drawing:

The word “dither” will be a useful name to give that elusive quality, that play on mechanical accuracy, existing in all vital art. It is this vital quality that has not yet received much attention in art training….

What is “dither,” exactly?

I am told that if you construct a perfectly fitted engine —the piston fitting the cylinder with absolute accuracy and the axles their sockets with no space between, &c.—it will not work, but be a lifeless mass of iron. There must be enough play between the vital parts to allow of some movement; “dither” is, I believe, the Scotch word for it. The piston must be allowed some play in the opening of the cylinder through which it passes, or it will not be able to move and show any life. And the axles of the wheels in their sockets, and, in fact, all parts of the machine where life and movement are to occur, must have this play, this “dither.”

Academic drawings don’t dither. They are overworked:

It has always seemed to me that the accurately fitting engine was like a good academic drawing, in a way a perfect piece of workmanship, but lifeless. Imperfectly perfect, because there was no room left for the play of life. And to carry the simile further, if you allow too great a play between the parts, so that they fit one over the other too loosely, the engine will lose power and become a poor rickety thing. There must be the smallest amount of play that will allow of its working. And the more perfectly made the engine, the less will the amount of this “dither” be….

This lifelessness infects photographs unless special care is taken to “ambiguate” them:

It is here that the photograph fails, it can only at best give mechanical accuracy, whereas art gives the impression of a live, individual consciousness. Where the recording instrument is a live individual, there is no mechanical standard of accuracy possible, as every recording instrument is a different personality. And it is the subtle differences in the individual renderings of nature that are the life-blood of art. The photograph, on account of its being chained to mechanical accuracy, has none of this play of life to give it charm. It only approaches artistic conditions when it is blurred, vague, and indefinite, as in so-called artistic photography, for then only can some amount of this vitalising play, this “dither” be imagined to exist.

While Speed describes this quality of dither somewhat romantically, I think that he is actually describing an operation of the mind: the constructive operations of vision. His vocabulary is different but the phenomenon described is the same.