凿壁借光
Bore a hole on the wall in order to get some light from the neighbour's house
匡衡年轻时十分好学。他家里很穷，买不起蜡烛，匡衡晚上想读书的时候，常因没有亮光而发愁。
  后来，他想了一个办法，就在墙壁上悄悄地凿了一个小孔。让隔壁人家的烛光透过来。就这样，他经常学到深夜，后来成了西汉著名的学者，曾做过汉元帝的丞相。从凿壁借光的事例可看出:外因(环境和条件)并不是决定性的因素，匡衡在极其艰难的条件下，通过自己的努力学习和坚强毅力，终于一举成员。
  这就说明内因才是事物发展、变化的根据和第一位的原因，外头因只是影响事物变化的条件，它必须通过内因才能起作用。
Kuang Heng when young and eager to learn。 His family was very poor, can not afford to buy a candle, when you want to read the Kuang Heng night, often worrybecause there is no light。
   Later, he thought of a way, in the wall secretly make a small hole。 Let the next family candlelight through。 In this way, he often until late into the night, and later became a famous scholar in the Western Han Dynasty, hadthe emperor's prime minister。
   From the examples to make a hole in the wall can be seen: external (environment) is not the decisive factor, the Kuang Heng in extremely difficult conditions, through my own efforts and perseverance, and finally at one fell swoop members。
   This suggests that internal cause is the thing changeaccording to the development, and the first cause, because just outside influence things changing conditions, it must work through the internal factors。