For more than two thousand years a familiarity with mathematics has been regarded as an indispensable part of the intellectual equipment of every cultured person. Today, unfortunately, the traditional place of mathematics in education is in grave danger. The teaching and learning of mathematics has degenerated into the realm of rote memorization, the outcome of which leads to satisfactory formal ability but does not lead to real understanding or to greater intellectual independence. This new edition of Richard Courant's and Herbert Robbins's classic work seeks to address this problem. Its goal is to put the meaning back into mathematics. Written for beginners and scholars, for students and teachers, for philosophers and engineers, What is Mathematics?, Second Edition is a sparkling collection of mathematical gems that offers an entertaining and accessible portrait of the mathematical world. Covering everything from natural numbers and the number system to geometrical constructions and projective geometry, from topology and calculus to matters of principle and the Continuum Hypothesis, this fascinating survey allows readers to delve into mathematics as an organic whole rather than an empty drill in problem solving. With chapters largely independent of one another and sections that lead upward from basic to more advanced discussions, readers can easily pick and choose areas of particular interest without impairing their understanding of subsequent parts. Brought up to date with a new chapter by Ian Stewart, What is Mathematics?, Second Edition offers new insights into recent mathematical developments and describes proofs of the Four-Color Theorem and Fermat's Last Theorem, problems that were still open when Courant and Robbins wrote this masterpiece, but ones that have since been solved. Formal mathematics is like spelling and grammar--a matter of the correct application of local rules. Meaningful mathematics is like journalism--it tells an interesting story. But unlike some journalism, the story has to be true. The best mathematics is like literature--it brings a story to life before your eyes and involves you in it, intellectually and emotionally. What is Mathematics is like a fine piece of literature--it opens a window onto the world of mathematics for anyone interested to view.

R·柯朗（Richard Courant）是20世紀傑齣的數學傢，哥廷根學派重要成員。他生前是紐約大學數學係和數學科學研究院的主任，該研究院後被重命名為柯朗數學科學研究院。他寫的書《數學物理方程》為每一個物理學傢所熟知；而他的《微積分學》已被認為是近代寫得最好的該學科的代錶作。

H·羅賓（Herbert Robbins）是新澤西拉特傑斯大學的數理統計教授。

I·斯圖爾特（Ian Stewart）是沃裏剋大學的數學教授，並且是《自然界中的數和上帝玩色子遊戲嗎》一書的作者；他還在《科學美國人》雜誌上主編《數學娛樂》專欄；他因使科學為大眾理解的傑齣貢獻而在1995年獲得瞭皇傢協會的米凱勒法拉第奬章。