As regards the style of Polygnotus we can glean a few interesting facts from our ancient authorities.  His figures were not ranged on a single line, as in contemporary bas-reliefs, but were placed at varying heights, so as to produce a somewhat complex composition.  His palette contained only four colors, black, white, yellow, and red, but by mixing these he was enabled to secure a somewhat greater variety.  He laid his colors on in “flat” tints, just as the Egyptian decorators did, making no attempt to render the gradations of color due to varying light and shade.  His pictures were therefore rather colored drawings than genuine paintings, in our sense of the term.  He often inscribed beside his figures their names, according to a common practice of the time.  Yet this must not be taken as implying that he was unable to characterize his figures by purely artistic means.  On the contrary, Polygnotus was preeminently skilled in expressing character, and it is recorded that he drew the face with a freedom which archaic art had not attained.  In all probability his pictures are not to be thought of as having any depth of perspective; that is to say, although he did not fail to suggest the nature of the ground on which his figures stood and the objects adjacent to them, it is not likely that he represented his figures at varying distances from the spectator or gave them a regular background.

It is clear that Polygnotus was gifted with artistic genius of the first rank and that he exercised a powerful influence upon contemporaries and successors.  Yet, alas! in spite of all research and speculation, our knowledge of his work remains very shadowy.  A single drawing from his hand would be worth more than all that has ever been written about him.  But if one would like to dream what his art was like, one may imagine it as combining with the dramatic power of Euphronius and the exquisite loveliness of the Aphrodite cup, Giotto’s elevation of feeling and Michael Angelo’s profundity of thought.

Another branch of painting which began to attain importance in the time of Polygnotus was scene-painting for theatrical performances.  It may be, as has been conjectured, that the impulse toward a style of work in which a greater degree of illusion was aimed at and secured came from this branch of the art.  We read, at any rate, that one Agatharchus, a scene-painter who flourished about the middle of the fifth century, wrote a treatise which stimulated two philosophers to an investigation of the laws of perspective.

The most important technical advance, however, is attributed to Apollodorus of Athens, a painter of easel pictures.  He departed from the old method of coloring in flat tints and introduced the practice of grading colors according to the play of light and shade.  How successfully he managed this innovation we have no means of knowing; probably very imperfectly.  But the step was of the utmost significance.  It meant the abandonment of mere colored drawing and the creation of the genuine art of painting.