A proof is a way to convince yourself and others that something is true.
语言是存在的家。在其家中，人居住。那些用语言思考和创造的人是这个家的守护者。
All changes follow a law.
Children totally accept — and crave — family rules. “In our family we have a rule for X” is the only excuse a parent needs for setting a family policy. In fact， “I have a rule for X” is the only excuse you need for your own personal policies.