"I will think of it." It is easy to say this, but do you know what great things have come from thinking?
Sir Isaac Newton was sitting in his garden when he saw an apple fall from a tree. He began to think and tried to find out why the apple fell. Then he discovered how the sun, the moon, and stars are kept in their places.
James Ferguson was a boy with little money. Once, seeing the inside of a watch, he wondered.
"Why should I not make a watch?" but how could he get the material to make the mainspring （钟表的主发条）? He soon found he could make it with whalebone （鲸须）. He then made a wooden clock which kept good time. His motto （座右铭）
Boys and girls, when you have a difficult lesson to learn, don't lose heart, and by thinking you will learn how to think to some purpose.
