Every picture conveys the feeling, often aroused by the composition itself, that at any moment some movement may begin. A simple experiment will show what this means. The illustration shows three identical male heads, schematically represented; yet, from left to right, the heads express first, active resolution on some reaction; next, moderation, patience, and self-possession; lastly, resignation to what is apparently seen.
This is not the author's interpretation, but the opinion, formulated more or less exactly, of eleven out of fourteen people (two saw no difference, one thought they were three different heads). This makes it clear that the placing of the subject, that is to say the composition of the picture, can have a vital influence on its effect and character. It is equally revealing to tilt the subject instead of moving it from side to side; as the head is held at different angles, its expression alters.
Expression is always made up of gesture and pose; both can be properly conveyed only by a relation to the horizontal and vertical axes, which are determined by the borders of the picture. The object's relation to the vertical and horizontal is the main indication of whether it is represented in movement or at rest. The determinant is the supposed line of gravity, which is always vertical; the base line is less important. An object can give a firm impression of rest even with a sloping base.
All bodies, which in pictures means all surfaces, fall down if their vertical axes fall beyond their base lines. The posture must express either helpless loss of balance or a willed movement. Whenever the line of gravity signifies a movement in progress, the picture gives the impression of arrested action, like the sudden stopping of a moving film. Sooner or later it becomes ridiculous unless some static rest can be felt; in other words, the figure should be able to remain in this position, at least momentarily, in reality.
This is a simple fact, easily proved. Here is an example taken at random. If you wish to represent a ball thrown up high, the only moment for representing it which is not ridiculous is when the ball has reached its highest point and for a fraction of a second stays there before it begins to fall. This is called the moment of rest. This rule applies equally to depicting a dancer, a discus thrower, or someone stepping forward. This is how Hodler represented his woodcutter: the axe has just reached the point of rest between swinging back and coming forward.
If you look at the figure for a long time you can even imagine that the axe has passed the moment of rest. In an internal combustion engine it would be the moment of late firing (after the moment of rest), known to give more power than early firing (before the moment of rest), which is better for acceleration. This analogy fits the depiction of a movement exactly. The sense of speed is greatest if the movement is seized just before its completion; just after the moment of rest gives the sensation of greatest impending impetus. But to catch precisely the moment of rest
itself may arrest all sense of movement.
The woodman would seem to be hanging by his axe handle, not swinging it.
The beholder likes to feel impending movement more than to see it, just as he likes to feel the depth and modeling of a picture grow on him and not have it thrust at him at first glance. If a stroke is given enough space to run on, you will feel that it has not only moved to a certain point but that it will move on or is already moving again. If you give it space at either end, the stroke seems to swing.
In this way movement can be represented which really seems, for a few seconds, to be going on in the picture. It is a trick, if you like; but this is not a degradation of means. Every craft has its tricks and dodges. This trick for depicting movement was first used intentionally by the Impressionists, although it existed earlier. There is, for example, the famous, mysterious smile of Leonardo's Mona Lisa. The mouth, or, more precisely, the corners of the mouth, seems to be moving, which has never ceased to be impressive and astonishing. It is this sensation that gives the smile its expressive power. The trick resides in the vague sfumato painting of the corners of the mouth, which are given space to move up or down or outwards, and seem really to do so. How quickly, in contrast, one tires of a fixed, full smile which has no possibilities of altering!
Mystery is the universal trick of all pictures which move us. The problem is how to achieve it. There is no doubt that in most cases it comes by chance. The artist's genius resides in his recognition of it, and in his not trying to alter or improve it. There is real art in omission, in implication, rather than complete statement.