The visual elements are points, lines, planes and volumes. These are the most basic elements from which the visual language is built up.
Spatially, a moving point gives rise to a line (the one dimension), a moving line moving in a direction other than its own intrinsic direction becomes a plane (the two dimensions) and a plane moving in a direction other than its own intrinsic directions becomes volume (the three dimensions).
Conceptually, we feel that there is a point at the intersection of lines, a line marking the boundary of a shape and that there are planes enveloping an object.