1 {scene: Isaac Newton's bedchamber, Cambridge}
1 Isaac Newton: {lying in bed} Hmmm... Sunday morning.
2 Isaac Newton: I think I'll just sleep in.
3 {beat}
4 Isaac Newton: After all, a body at rest likes to remain at rest.

This is of course a simple statement of part of Newton's First Law of Motion. A more usual simple form of the law is something like:

A body in a state of rest or uniform motion remains in that state unless acted upon by a net external force.

This basically says two things:

1. Something which isn't moving stays still unless something pushes it or pulls on it. Pretty obvious and in line with our everyday experiences. An object can also move if it itself produces a push or pull on nearby objects. This covers the case of self-powered objects like animals or vehicles, which can move without something else pushing them - basically they push themselves. Nothing really special there.
2. Something which is moving will keep moving at the same speed, and in the same direction, unless something (including itself) pushes or pulls it. This one isn't quite so obvious. After all, if you kick a ball along some grass, it doesn't keep going at the same speed. It slows down and eventually stops. But what's happening here is that frictional forces between the ball and the ground act on the ball, slowing it down. If you could get rid of the friction, the ball would indeed not slow down.

It was this second part that really established the framework of modern mechanics (i.e. the physics of forces and motion). Other people had essentially formulated the same statement before Newton - notably Galileo and Descartes - but Newton took it and used it as the foundation for his theory of motion, which was the first really successful treatment of the physics involved.

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2022-05-15 Rerun commentary: It's lucky Newton didn't know about Einsteinian relativity, because then he'd know that time is merely an illusion. Lunchtime doubly so.