To formulate [the principle of inertial motion] required a remarkable detachment from the world of experience, for such a motion is nowhere observed, ever, uniform motion in a straight line without any force acting upon the body.
It requires one to envisage a perfectly empty universe, with one sole object moving through space. It would then perform this inertial motion in a straight line. No-one could tell this because there would be no ruler and clock, and if there were, then the motion would no longer be in a straight line, because gravity would make it curve.
I dedicate this quote to all the Newtonian physics teachers still fanatically teaching this absurd notion of inertial motion on a straight line as a law of nature.
Notes:
--- The quote is from Nick Kollerstrom, Isaac Newton: Science's Greatest Fraud, p.70)
