PICTORIAL REPRESENTATION

Throughout the world delineation, whether incised, drawn or painted, has been a means of attaining one of the prime aims of pictorial art: the isolation of an object from the array of colored patches the eye sees in nature. The earliest known paintings, in French and Spanish caves (see pp. 38-42), are profiles of animals unrelated to earth or sky or one another. Composite groups came later and the defined image field - that is to say, an enclosed area within which all the forms are interrelated - later still with the invention of framing devices. Even in some of the most sophisticated forms of two-dimensional art, the images are all that count, the field on to which they are projected being no more than part of an undefined ground, not a background in the Western sense. In ancient Egypt it was often covered with hieroglyphic inscriptions. On Chinese scroll paintings poems are often written in the 'sky'.

Images have been drawn and painted conceptually (according to what the mind knows) or perceptually (according to what the eye sees at a particular moment). A conceptual image can, in theory, record the salient characteristics of any object by taking it apart and reassembling it - front, back and sides - so that all are visible. (The recent term 'Conceptual Art' has, of course, an entirely different meaning) Perceptual images are attempts to record the truth of visual appearances, though in practice they are inevitably influenced by what painters know about not only the physical properties of a subject but also the ways in which it has previously been depicted. And they, too, may be combined in a conceptual manner. All images are to some extent both perceptual and conceptual.

Perspective

In many, perhaps most, drawings and paintings apart from those produced in Europe between the fifteenth and twentieth centuries, differences in the size of figures signify their relative importance - a deity and worshippers, a ruler and courtiers, sometimes a man and woman - rather than their physical distance from one another and the foreground. When figures are not all ranged on a single plane like actors before a curtain, diminution may also sometimes have been intended to suggest recession in space. In an eighth-century BC Assyrian relief, for instance, three officials are very much larger than neighbouring captives and a man driving away a flock of sheep (3,28). Their arrangement in three tiers indicates distance. The artist's aim was to record an event. Much later, various techniques were devised to represent on a flat surface the appearance of such three-dimensional objects as buildings. Greek vase painters from about the fourth century BC and ancient Roman mural painters adopted a system of axial perspective by which such parallels as the walls of an interior, the beams of its ceilings or the tiles of its floor were shown converging symmetrically on a central axis.

Chinese artists evolved a logical perspective technique for representing buildings, usually from above. As they expected a horizontal scroll to be studied while it was being slowly unrolled they had no need to depict a panorama from a single viewpoint. Each group of buildings could have a perspective coherence unrelated to those on either side. Sometimes buildings in close proximity were shown as if seen from slightly different viewpoints - as in a section of an early twelfth-century scroll where one looks down on the roofs of houses but can also see the underside of the bridge (0,7).

European artists adopted various devices to suggest, rather than represent, three-dimensional forms during the Middle Ages. Interiors were often shown in axial perspective, as in Giotto's Marriage Feast at Carta (9,83) where the walls of the room which seem to slant inwards were presumably intended to be understood as parallel, joining the far wall at right-angles. Not until the early fifteenth century was it noticed that all receding parallel lines at right angles to the field of vision - called orthogonals - appear to converge on a single distant vanishing-point. This was the basic assumption underlying the theory of linear perspective first used for a painting by Filippo Brunelleschi in about 1415 and codified in a treatise of 1435 by Leon Battista Alberti - both of them Florentine architects. The effect of this discovery may be clearly seen if a townscape by Ambrogio Lorenzetti of 1339 (9,86), in which each building is depicted from a separate viewpoint, is compared with the rationally ordered An Ideal Town (10,24) painted about a century later. In the latter the whole view is shown from a single viewpoint and the orthogonals, following the roof lines of the buildings on either side of the piazza and the lines of the pavement, converge towards a vanishing-point behind the door of the central structure. Lorenzetti gives a realistic impression of a haphazard urban environment in which strangers might lose their way. An Ideal Town is depicted so precisely that accurate measured drawings could be made of its plan and of the facade of every building. Painters and also sculptors of low reliefs in Italy, mainly in Florence, soon adopted the geometric network of orthogonals to indicate the position of human figures receding into a background, as in Masaccio's Tribute Money (10,6). Beautiful in their logical simplicity though such one-point perspective systems were they did not solve all the problems confronting artists in rendering space and variations had to be introduced - two or more vanishing-points, for example, might be combined, as by Donatello in his relief of St Anthony Healing the Young Man's Foot (0,8). And further, more complicated and sophisticated adjustments were made. Yet it was always recognized that these optical rules were no more than an aid to pictorial representation. Indeed they were ignored completely by Netherlandish artists until the sixteenth century. They had their own empirical means of indicating recession: there is, for instance, no single vanishing-point in Jan van Eyck's Madonna of Chancellor Rolin (10,13). In Italy, Andrea Mantegna was one of several artists who mastered the principles of linear perspective well enough to depart from them when desirable. In his painting of the Dead Christ (0,9), for instance, which might almost seem to be a demonstration in the art of foreshortening, considerable liberties were taken with perspective. In a geometrical projection the feet would be very much larger and the head smaller than depicted by Mantegna.

Color

The development of systems of perspective coincided with the emergence of the peculiarly Western concept of a painting as a window on to a real or imaginary world, and for this color was no less necessary than drawing. Color is scientifically defined as the sensation produced on the eye by rays of light striking a surface that reflects some of them and absorbs others. This followed on Isaac Newton's demonstration in 1672 that natural light if passed through a prism is dispersed into the spectrum of chromatic rays, as is seen in a rainbow (the effect of sunlight refracted through raindrops). These rays can be separated into primary colors - red, yellow and blue - and secondary colors (i.e. green from blue and yellow) into which they merge. He believed that these colors would form a wheel with red at one end of the band merging into violet; those at opposite sides of the wheel (red-green, yellow-violet, etc.) came to be called complementary (0,10). Newton's explanation of the phenomenon of color was revolutionary even though it owed much to earlier theories and experiments. But it made far less impact than the invention of linear perspective on artists. They had already discovered in practice the effects that could be obtained by mixing, superimposing and contrasting pigments, few of which exactly corresponded with the colors of objects seen in nature. They had also, like Rubens, noted the colors of the rainbow.

From the earliest times, artists used colored pigments to define images by outline. Throughout the world the great majority of paintings have been executed in this linear way, with strongly marked contours which are, of course, rarely apparent in nature. Not until the late fifteenth century did European artists begin to use color to define forms without outlines, in what is nowadays called a painterly technique, facilitated by the development of oil paint. They also began to distinguish between the colors of objects seen in clear diffused daylight, called local color, and those taken on by juxtaposition, by reflection - as in the glow of the setting sun - and when seen at a distance. The value, that is to say the lightness or darkness of a color, appears to be modified by juxtaposition with one that is darker or lighter. Flesh tones look pale against a red background but reddish against yellow. The modelling of forms in chiaroscuro was more effectively suggested by taking reflected light into account than by shading a single color. Aerial perspective was devised in order to indicate distance in a landscape, for instance, without a network of orthogonals but by muting color contrasts and grading tones - as in the Virgin and Child with St Anne by Leonardo da Vinci (11,14). To emphasize aerial perspective painters often introduced a repoussoir, a prominent dark form in the foreground or middle distance, such as a large tree in a landscape.

Linear perspective, aerial perspective and chiaroscuro enabled painters to trick the viewer's eye (trompe I'oeil). By adopting a complex system of foreshortening, they learned to depict on ceilings figures hovering in the sky or posed on balustrades so cunningly rendered that they might at first sight seem to be part of the real three-dimensional surface of the walls. But illusionism was rarely pursued as an aim in itself. When it was, the artists intended it as a virtuoso performance of their cleverness in 'fooling the eye'. Painters in the West, from the fifteenth to the mid-nineteenth century, aimed for verisimilitude, an appearance of visual truth - an equivalent to the view through the opening in a wall or ceiling. Different degrees of verisimilitude were thought appropriate for different subjects: a religious image, a landscape, a genre scene recording daily life, the portrait of a ruler or that of a friend of the artist. But in general verisimilitude was sought because it enforced the message of an image by implying that what was true to visual appearances was true in other respects.

soul'. The content of his paintings was, he said, 'what the spectator lives or feels while under the effect of form and color combinations' (see p. 792). Subsequently, forms were to be eliminated from many-non-representational paintings altogether, especially in the USA after World War II.

Pure color is the subject of Ellsworth Kelly's Spectrum III of 1967,13 strips of pure hues of the natural spectrum, but not merging into one another as in a rainbow, and with yellow at the two ends, red and violet in the middle (0,11). The painting shows the sensed but scientifically undemonstrable effects on the eye of juxtaposed colors; for although the strips are of equal width (except for those at either end) some seem wider than others, the warm reds seem to advance in space, the cool blues and greens to retract. With its reference to the theories initiated by Newton, this painting indicates the disjunction between science and art: how colors are defined scientifically and how they are experienced, not by the eye alone.

Many theoretical writings on optics were published in the eighteenth and nineteenth centuries, a few of them by artists. But painters appear to have learnt the effects of mixed and juxtaposed colors less from theories than by practice, by studying the works of others and especially by handling pigments in the studios of their teachers who imparted the manual and other skills passed on from one generation to the next. This accounts for the continuities in the history of pictorial representation - the persistance of schemata or visual formulae - though it has not, of course, prevented change as artists have discovered for themselves and explored new means to give expression to their individual vision.

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