A manual labourer must have a limit on his hours， otherwise he will wear himself out. If he intends to remain always a manual labourer， then he should forget about his work when the whistle blows， but if he intends to go forward and do anything， the whistle is only a signal to start thinking over the day’s work in order to discover how it might be done better.
The man who has the largest capacity for work and thought is the man who is bound to succeed. I cannot pretend to say， because I do not know， whether the man who works always， who never leaves his business， who is absolutely intent upon getting ahead， and who therefore does get ahead—is happier than the man who keeps office hours， both for his brain and his hands. It is not necessary for any one to decide the question. A ten-horsepower engine will not pull as much as a twenty. The man who keeps brain office hours limits his horsepower. If he is satisfied to pull only the load that he has， well and good， that is his affair—but he must not complain if another who has increased his horsepower pulls more than he does. Leisure and work bring different results. If a man wants leisure and gets it—then he has no cause to complain. But he cannot have both leisure and the results of work.