Michelangelo 's greatest work here is reserved for two minor members of the family , Lorenzo 's grandson , Lorenzo the Duke of Urbino , portrayed as a pensive Roman soldier above two allegorical figures of Dawn ( female ) and Dusk ( male ) , and his son , Giuliano the Duke of Nemours , more warrior-like above figures of Night ( female ) and Day ( male ) .
Michelangelo 's best work was only for the head of the family .