As a boy,Carl said he knew if it was time to go to school by the sound of a train.

VOA: special.2009.11.01

When Thoreau sits on his little stool outside his cabin at Walden Pond and he hears the train go by over the ridge, and he puts his hands over his ears he doesn't want to hear it-- he's representing something.

在瓦尔登湖的木屋外,梭罗坐在他的小凳子上,他听到火车的声音穿越桥梁,他捂住了耳朵,他一点也不想听到这个声音,他代表着某种想法

耶鲁公开课 - 美国内战与重建课程节选