Nature Is Pleased With Simplicity And

The first part of this quote — "Nature is pleased with simplicity, and affects not the pomp of superfluous causes" — appears authentically in Newton's Philosophiæ Naturalis Principia Mathematica (1687), as the rationale for Rule 1 of his Rules of Reasoning in Philosophy. It articulates what we now call the principle of parsimony. The appended phrase "And nature is no dummy" does not appear in the Principia text and is a modern addition of uncertain origin.