Full Idea
It is possible that there is no uniform motion by which time may have an exact measure. All motions can be accelerated and retarded, but the flow of absolute time cannot be changed.
Gist of Idea
If there is no uniform motion, we cannot exactly measure time
Source
Isaac Newton (Principia Mathematica [1687], Def 8 Schol)
Book Reference
Newton,Isaac: 'Philosophical Writings' [CUP 2004], p.66
Related Idea
Idea 17012 Time exists independently, and flows uniformly [Newton]