Sentence:  If , on the other hand , they opted for representation , it had to be representation per se - representation as image pure and simple , without connotations ( at least , without more than schematic ones ) of the <WSD>three-dimensional</WSD> space in which the objects represented originally existed . 
Meaning of the word marked with <WSD> tags:  involving or relating to three dimensions or aspects; giving the illusion of depth