Or we can pass from this simplified propaedeutic to the problems of the real world in which our previous expectations are liable to disappointment and expectations concerning the future affect what we do to-day.

或者我们可以从这个简化的预科过渡到现实世界的问题，在现实世界中，我们以前的期望很容易失望，而对未来的期望会影响我们今天的行为。