draw the line at, to

To set a specific limit, particularly on one’s behav- ior. This expression, heard in such contexts as “He drew the line at outright cheating,” comes from drawing some sort of boundary, but no one is quite certain as to what kind. Some speculate it comes from the early game of court tennis, in which the court had no specific dimensions and the players had to draw their own lines. Others believe it signified a line cut by a plow across a field to designate the property boundary. The term was used figura- tively from the late eighteenth century on and was probably a cliché by the time W. S. Gilbert wrote, “I attach but little value to rank or wealth, but the line must be drawn somewhere” (H.M.S. Pinafore, Act I).