Thinking more about this, my answer to "why learn calculus" is that so many ideas and tools of modern life are explained, and even relate to one another, throug

Thinking more about this, my answer to "why learn calculus" is that so many ideas and tools of modern life are explained, and even relate to one another, through calculus. Without calculus, many simple things become unapproachable, or have to be approached by rote learning of formulas and rules. When in grad school, a friend of mine taught a freshman course on modern history, and in the first week he introduced a general outline of calculus. The students were surprised, but he explained that calculus is a thread woven through modern history thanks to the importance of science and technology.