An interesting lecture by Anthony J. Brankin:
Ask any child who is drawing something what he is trying to do and he will tell you that he is trying to recreate something that he saw in nature, be it an apple, or the sun, or a tree, or a house. And, invariably, the measure of the success of the drawing for that child is how closely the drawing resembles nature.
Accuracy according to nature was always the standard of reference for artists and societies, for all high civilizations from the Egyptians and Greeks to the Romans and Europeans. Each culture’s succeeding generations of artists tried to improve upon, or at least remember, the techniques, lessons, and discoveries of the previous generations, always seeking a greater beauty of lines, more solid figures, and truer perspectives.