The idea of limit is the basic idea of calculus and a series of important concepts in mathematical analysis, such as continuity of function, derivative (maximum value is 0), definite integral and so on. These are all defined by the way of limit.

Extreme thinking method is an indispensable and important method in mathematical analysis and even all higher mathematics, and it is also the development of "mathematical analysis" and "elementary mathematics" with continuity and further thinking.