The ** Philosophiae Naturalis Principia Mathematica** (Latin: "mathematical principles of natural philosophy", often

In formulating his physical theories, Newton had developed a field of mathematics known as calculus. However, the language of calculus was largely left out of the *Principia.* Instead, Newton recast the majority of his proofs as geometric arguments.

It is in the *Principia* that Newton expressed his famous *Hypotheses non fingo* ("I feign no hypotheses", that is, "I do not assert that any hypotheses are true"). Here is the passage containing this famous remark:

- I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.''

*Of The Motion Of Bodies**Of The Motion Of Bodies (contd.)**The System Of The World*