- § 303. The infinitesimal has been usually supposed essential to the calculus
- § 304. Definition of a continuous function
- § 305. Definition of the derivative of a function
- § 306. The infinitesimal is not implied in this definition
- § 307. Definition of the definite integral
- § 308. Neither the infinite nor the infinitesimal is involved in this definition

The Principles of Mathematics was written by Bertrand Russell, and published in in 1903. It is now available in the Public Domain.