The essence of the answer lies in a quip that the physicist Richard Feynman made to the novelist Herman Wouk when they were discussing the Manhattan Project. Wouk was doing research for a big novel he hoped to write about World War II, and he went to Caltech to interview physicists who had worked on the bomb, one of whom was Feynman. After the interview, as they were parting, Feynman asked Wouk if he knew calculus. No, Wouk admitted, he didn’t. “You had better learn it,” said Feynman. “It’s the language God talks.” — *location: 41* ^ref-29620 --- The Infinity Principle To shed light on any continuous shape, object, motion, process, or phenomenon—no matter how wild and complicated it may appear—reimagine it as an infinite series of simpler parts, analyze those, and then add the results back together to make sense of the original whole. — *location: 188* ^ref-57709 --- The Infinity Principle organizes the story of calculus around a methodological theme. — *location: 204* ^ref-48236 --- We feel we are discovering mathematics. The results are there, waiting for us. They have been inherent in the figures all along. We are not inventing them. — *location: 965* ^ref-4971 --- From a modern perspective, there are two sides to calculus. Differential calculus cuts complicated problems into infinitely many simpler pieces. Integral calculus puts the pieces back together again to solve the original problem. — *location: 1521* ^ref-26399 --- “Art,” said Picasso, “is a lie that makes us realize truth.” The same could be said for calculus as a model of nature. — *location: 2622* ^ref-53359 --- Elegant solutions are valued in math in part because they’re pretty but also because they’re powerful. The light they shed can often be used to illuminate other problems. — *location: 3343* ^ref-51086 --- They would be, in the words of the Hungarian mathematician Paul Erdős, proofs straight from the Book. Erdős imagined that God kept a book with all the best proofs in it. Saying that a proof was straight from the Book was the highest possible praise. — *location: 4600* ^ref-21693 ---