Once, in a rush season, an office boy was kept working overtime for several nights. He didn't like it, and growled to his boss: "You've kept me workin' every night till 9 o'clock for three nights runnin' now, and I'm worn out, Mr. Brown. I ain't no machine. I can't go forever." His boss gave a hard laugh. "Wrong!" he said. "Wrong, my boy. You go forever next pay day."