Full Idea
Newton works with four fundamental concepts: space, time, matter and force.
Gist of Idea
Newton's four fundamentals are: space, time, matter and force
Source
report of Isaac Newton (Principia Mathematica [1687]) by Bertrand Russell - My Philosophical Development Ch.2
Book Reference
Russell,Bertrand: 'My Philosophical Development' [Routledge 1993], p.12
A Reaction
The ontological challenge is to reduce these in number, presumably. They are, notoriously, defined in terms of one another.