Sentence:  But at the end of the <WSD>sitting</WSD> , when Michelangelo showed him the quick , free drawings , with the mother roughed in , holding her son , the model grasped what Michelangelo was after , and promised to speak to his friends . 
Meaning of the word marked with <WSD> tags:  (photography) the act of assuming a certain position (as for a photograph or portrait)