I assume he's referring to this [1], although Newton invented his calculus because he couldn't use this approach to solve practical problems. [1] http://en.wik

I assume he's referring to this [1], although Newton invented his calculus because he couldn't use this approach to solve practical problems. [1] http://en.wikisource.org/wiki/The_Mathematical_Principles_of_Natural_Philosophy_(1846)/BookI-I http://en.wikisource.org/wiki/The_Mathematical_Principles_of...