"Ever since the discovery of perspective or other techniques involving color, pictures - figurative or abstract - have had the ability to relay the impression of space, and hence, require no further remark.

Accordingly, space is just a recurrence of that which (or how) we actually see anyway. Then again, when dealing with "depth" more is actually required than simply that. Still, can another form of depth successfully operate if our related concepts of space are bound on the habit of perspective seeing, and indeed don't expect otherwise of a picture's space? In other words, are there other forms of depth than that of space; or other ways to bring it into a picture other than using perspective?

The reader needs only recall the art of ornament which underscores the importance of the object on which it�s fixed. The intention here was: the exterior surface interprets the inner depth. Divination techniques for older civilizations along with diverse lineament on turtle shells, in animal entrails, in flights of birds - taken as a sign of mystery - must have been a familiar way of thinking. Thus, depth wasn�t only spatial distance, inasmuch as the contrary, invisible side of the range of sight. The renaissance school of disegno - up until its deconstruction - took up the idea again, to the extent of Hogarth�s interpretation, that a line, vigourous drawn, reveals how the art work sees itself from the inside out. In those days beauty was formerly described as balanced proportion, and was therefore challenged with the question, for what other purpose disegno, linear beauty, arabesque, or ornament could serve - if not, at least to conceal weaker points in an art work."

From www.spacetime-publishing.de/luhmann/blackholes-e.htm