Dots are just one example of an element in Lascaux art, and in all cave art... This is a profusion of nonrepresentational, geometric patterns. In addition to dots, there are grids and chevrons, curves and zigzags, and more.... The coincidence of these geometric motifs with representational images is one of the most puzzling aspects of Upper Paleolithic art.... images, six different kinds in all, are shimmering, incandescent, mercurial—and powerful. Called entoptic images—which means "within vision"—these phenomena are products of the basic neural architecture of the human brain.

Origins Reconsidered: In Search of What Makes Us Human (1992)