OF ORDINARY PERSPECTIVE.

An object of equal breadth and colour throughout, seen against a
background of various colours will appear unequal in breadth.

And if an object of equal breadth throughout, but of various
colours, is seen against a background of uniform colour, that object
will appear of various breadth. And the more the colours of the
background or of the object seen against the ground vary, the
greater will the apparent variations in the breadth be though the
objects seen against the ground be of equal breadth [throughout].