微积分发展历史，为何断裂？
  微积分发展历史，在时间轴上，表现为一个区间，其中不该发生断裂。
  微积分思想老祖宗阿基米德预见到解决微积分问题的两种方法：无穷小与 （ε,δ）极限方法。这是历史的事实。
  到了十九世纪，（ε,δ）极限理论护犊子彻底驱除无穷小方法，致使微积分发展历史出现断裂。
  到了二十世纪六十年代，鲁宾逊恢复了无穷小的名誉，弥补了微积分发展历史上的断裂。    
  请见本文附件。
袁萌  陈启清  12月8日
附件：
Epllogue（无穷小微积分课程的结束语）
  How does the infinitesimal calculus as developed in this book relate to the traditional (or e, 3) calculus? To get the proper perspective we shall sketch the history of the calculus. Many problems involving slopes, areas, and volumes, which we would today call calculus problems, were solved by the ancient Greek mathematicians. The greatest of them was Archimedes (287-212 B.C.). Archimedes anticipated both the infinitesimal and the   （ε,δ）approach to calculus. He sometimes discovered his results by reasoning with infinitesimals, but always published his proofs using the "method of exhaustion," which is similar to the （ε,δ）  approach. Calculus problems became important in the early 1600's with the development of physics and astronomy. The basic rules for differentiation and integration were discovered in that period by informal reasoning with infinitesimals. Kepler, Galileo, Fermat, and Barrow were among the contributors. In the 1660's and 1670's Sir Isaac Newton and Gottfried Wilhelm Leibniz independently "invented" the calculus. They took the major step of recognizing the importance of a collection of isolated results and organizing them into a whole. Newton, at different times, described the derivative of y (which he called the "fluxion" of y) in three different ways, roughly
(1) The ratio of an infinitesimal change in y to an infinitesimal change in x. (The infinitesimal method.) (2) The limit of the ratio of the change in y to the change in x, l'ly/ l'lx, as l'lx approaches zero. (The limit method.) (3) The velocity of y where x denotes time. (The velocity method.)
In his later writings Newton sought to avoid infinitesimals