Robson, William: Grammigraphia; or the Grammar of Drawing. (London, 1799)

65
The PERSPECTIVE PLANE

Is Nature ; the real objects imaginarily viewed as on one
Perpendicular sheet like a picture; substance, property,
distance, reality lost, and appearance only remaining.
The knowledge of circumstances, and previous acquaintance
with them being dismissed from the mind.

This Plane presents to the eye Proportion, and Position
only ; and these two modifications of Appearance are frst
to be nicely calculated, and then described by Lines.