five o'clock
`` I must perforce . My model 's foot is on the stair . '' Amarilly left the studio to resume her cleaning . At five o'clock she came back . Derry stood at the window , working furiously at some fleecy clouds sailing over a cerulean sky . She was about to speak , but discerning that he must work speedily and uninterruptedly to keep pace with the shifting clouds , she refrained . `` There ! ''