The most important part of teaching is to teach what it is to know.
The division of labor is limited by the extent of the market.
无论是个人还是国家,只要生活节俭,就会繁荣昌盛;如果贪图享受,放纵欲望,那就会走向衰亡。
煤炭不仅仅是一种商品,更是现代文明赖以建立的基础。