Sentence:  Instead of isolating the literal flatness by specifying and circumscribing it , the pasted paper or cloth releases and spreads it , and the artist seems to have nothing left but this undepicted flatness with which to <WSD>finish</WSD> as well as start his picture . 
Meaning of the word marked with <WSD> tags:  come or bring to a finish or an end; others finished in over 4 hours"