<human>:  When did the concept of a limit come into mathematical analysis?
<bot>: The concept of a limit was first introduced by Leibniz in his work on infinitesimals. Leibniz was one of the first mathematicians to realize that the notion of a limit is a fundamental concept in mathematics. He also was one of the first to realize that there are many different kinds of limits, and that the concept of a limit can be generalized in many different ways.