Last week, we looked at the choice of medium in painting – why it matters, what the main options are, and how the properties of each shape the kind of image an artist can make. This week, we turn to the three elements that lie at the heart of the painted image: line, tone, and color. Together with the handling of detail and distance, these form the complete visual vocabulary that every artist draws on, whatever his tradition or period.
In this portrayal of a knight by the English monk Matthew Paris, from the 13th-century Westminster Psalter, we see a skilled use of line to depict form. Paris controls his line with enough assurance to give it a graceful, flowing quality, a beauty comparable to fine calligraphy. Notice also how he varies the width and darkness of his lines. He does this for two purposes: first, to direct the viewer’s eye toward the parts of the composition he considers most important, since a thicker, darker line draws attention more strongly; and second, to indicate the degree of contrast between an object and its background. Where a light shape sits against a much darker one, the contrast is high, and a bold line is appropriate; where a pale shape sits against a slightly darker background, the contrast is low, and only a thin, pale line is used. Where there is effectively no contrast at all, the skilled artist will allow the line to disappear entirely, even though he knows the edge of an object is there. The less skilled artist tends to put the line in anyway, because he knows intellectually that the edge exists, and this will overrule what his eyes are actually telling him. Line drawing is easy to do poorly – it is how most children begin – but demands genuine subtlety to handle well.
Where line represents contrast by marking a boundary, the second approach represents it by painting tonal values directly, as the eye sees them. This is harder than it sounds. Most people must be trained to observe what the eye actually sees rather than what the mind constructs after processing visual information, and what the mind constructs is always conditioned by memory and prior knowledge of the object. Consider this self-portrait by Rembrandt:
Here, there are no lines at all. Everything is a tonal value, and any apparent edge is simply the junction of a lighter and a darker area. This allows Rembrandt to convey the shape of the face without an outline. He is also willing to let edges dissolve where the tonal contrast is low: the right side of the figure here is barely distinguishable from the background. This points to a deeper distinction between the two approaches. Line tends to show edges and discontinuities; tonal painting can express the gradually changing internal variations of a three-dimensional surface, which is why it lends itself more to high naturalism.
In practice, most artists combine the two approaches, with one playing a supporting role to the other. Matthew Paris is a good example: predominantly linear, but with enough internal tonal variation to suggest the three-dimensional character of the forms. Having considered line and tone, we can turn to the third element – color – which brings its own particular difficulties.
Consider a grayscale image of something colored in nature. Red and yellow can generally be distinguished, since red tends toward a darker tonal value in monochrome, but red and blue are much harder to tell apart. I can remember watching Liverpool and Everton soccer matches on a black-and-white television in the 1960s: Liverpool in deep red, Everton in deep blue, indistinguishable from the waist up. Fortunately, Everton wore white shorts and Liverpool red, which settled the question. (I am a Liverpool supporter, incidentally.)
The reason this matters to the painter lies in how the eye works. The human eye reads both monochrome and color simultaneously, using different receptor cells (rods and cones) in the retina, and the brain can assess three-dimensional form from tonal and color variation in combination. But while the mind processes this information with ease, it is extremely difficult for the artist to represent it faithfully. Colors do not simply become darker or lighter in shadow. They may shift toward blue in shade, or toward yellow and green in bright sunlight, even though the actual color of the object has not changed. This means that to paint color accurately, the artist must observe what his eye receives rather than what his intellect tells him the color ought to be.
There is a further complication: colors shift not only with light and shadow, but also with distance, through what is called color perspective. The green of leaves becomes progressively bluer the further away they are, which is why mountain ranges always appear blue on the horizon - hence the song about the Blue Ridge Mountains of Virginia. Tonal contrast also decreases with distance, so that those blue mountains become not only bluer but lighter the further away they are. The skilled naturalistic artist must hold all of these variables in balance simultaneously, and few manage to do so well.
Here is one who did:
In Vermeer’s The Art of Painting (c. 1666), notice the large draped curtain pulled to one side. We judge the actual color of its pattern by looking at the mid-tones, the areas neither bleached by direct light nor lost in deep shadow. Vermeer has shifted the colors so that what is blue in full light becomes reddish in the shadow, and vice versa; yet the eye reads the fabric as a consistently colored pattern, because the brain automatically compensates for exactly this kind of variation. To do this in paint, Vermeer had to observe the colors as his eye received them, rather than as his intellect classified them, suppressing the very interpretive process by which we normally make sense of what we see. This capacity is rare. Most Baroque masters simplified the problem by concentrating on tonal variation and applying Vermeer’s kind of color sensitivity only at the main focal points.
Closely related to the handling of color and tone is the question of how the artist represents distance itself - not just the color shift of distant objects, but the whole problem of conveying size and space on a flat surface.
Yet this same principle, once understood, can be turned to deliberate and powerful effect. Artists who consciously heighten detail at apparent distances and, in doing so, deliberately override natural perception can imbue their images with a symbolic or heavenly quality. In heaven, to behold something fully is to know it fully; heightened detail across an entire picture plane suggests a mode of seeing that is not bound by natural distance. Gothic painters such as Duccio and Van Eyck, and iconographic painters such as Andrei Rublev, understood this and used it consistently. Their images carry a sense of participation in a different order of reality - one where the ordinary limits of perception do not apply. There is a skill in using this as a visual tool: for the break from naturalism to work, everything else present in the painting must support the idea that we are looking at heaven, so that the heightened level of detail no longer strikes the viewer as incongruous.
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| The Last Supper by Duccio, Italian early 14th century, egg tempera on wooden panel |
It is commonly said that a good artist knows the rules, and a great artist knows when to break them. I do not think this is quite right. These are not arbitrary rules but principles grounded in how images actually work, and the genuinely skilled artist does not break them - he applies them differently depending on what he is trying to represent. The same principle of detail and distance is applied one way when painting the natural world, where detail diminishes with distance, and another way when painting heavenly subjects, where it does not. What looks like rule-breaking is usually the consistent application of a different set of governing assumptions about the nature of the subject. The failure of the Pre-Raphaelites and photorealists is not that they broke the rules but that they applied naturalistic conventions to subject matter and compositions that would have been better served by something else, producing an incongruity they did not recognize and could not resolve.
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| Our English Coasts or Strayed Sheep, William Holman Hunt, Pre-Raphaelite tradition, English, 19th century; oil on canvas |

























