It assumes vertical and horizontal axes are parallel to the picture’s plane. All lines parallel to these axes are also parallel to the picture’s plane and therefore retain their true orientation without seeming to converge (Ching 250).
The two principle horizontal axes assume a slanting appearance to the image’s plane. All lines parallel to these axes appear to converge to two points that appear to be vanishing on the horizontal line (Ching 261).
I prefer the two-point perspective because it is more effective in illustrating the 3-dimensional outline of objects in space, ranging in scale, from a chair to the mass of a building. The spectator becomes an integral part of the space rather than a mere observer looking from the