> why does the plane look so uniformly covered? It's a purely perceptual effect. As you track away from the center of the spiral, your eyes are following lines

> why does the plane look so uniformly covered? It's a purely perceptual effect. As you track away from the center of the spiral, your eyes are following lines, which are one-dimensional, but you're tracking the lines through a plane, which is two-dimensional. The area increases rapidly as you move away from the center of the figure, but the one-dimensional lines don't have area. This gives the lines an apparent weight that they don't actually have.