Aerial perspective, and painting compared with sculpture
Why distant edges blur, and why painting asks more of the mind
The upper lines close an argument on the perspective of colours: a painter who lacks it makes the outlines of distant things as sharp as near ones, fails to let the interposed air veil the far object, and cannot render transparent bodies or coloured gravel seen beneath clear water. A new section, headed as the comparison of painting with sculpture, then argues that painting demands greater mental discourse and artifice. Sculpture, Leonardo says, is only what it appears, its relief and modelling owed largely to nature, whereas the painter adds the aid of perspective and its foreshortenings. The text is in a neat humanist hand and breaks off with the sculptor's reply.
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The perspective of colours and the blurring of distant edges
Without the perspective of colours a painter makes the outlines of near and far things equally distinct, and does not let the air between the distant object and the eye veil it more than the near one. Nor can he render lucid and transparent bodies like veiled figures showing flesh beneath, nor the fine gravel of many colours beneath the surface of clear water. This describes what aerial perspective supplies to a picture.
Comparison of painting with sculpture
Painting is said to be of greater mental discourse and artifice than sculpture, since sculpture is nothing but what it appears, a body in relief clothed with light and dark like other natural bodies. Its modelling is carried out by two agents, nature and man, but nature's part is far the greater. The painter, by contrast, adds the aid of perspective, whose foreshortenings turn the muscular surface of bodies to different aspects, one muscle overlapping another.