These sciences have no principles besides definitions and axioms, and no process of proof but deduction; this process, however, assuming a most remarkable character; and exhibiting a combination of simplicity and complexity, of rigor and generality, quite unparalleled in other subjects.

The Philosophy of the Inductive Sciences Founded Upon Their History - (Volume 1), Part 1, Book 2, Chapter 1, Section 2 (p. 83)