Sentence:  Instead of isolating the literal flatness by specifying and circumscribing it , the pasted <WSD>paper</WSD> or cloth releases and spreads it , and the artist seems to have nothing left but this undepicted flatness with which to finish as well as start his picture . 
Meaning of the word marked with <WSD> tags:  a material made of cellulose pulp derived mainly from wood or rags or certain grasses