The unification that started modern science
Before Newton, falling apples and orbiting moons were separate phenomena. Apples obeyed earthly physics. Heavenly bodies obeyed perfect celestial geometry. Two domains, two sets of rules.
Newton's leap was simple and outrageous: both are doing the same thing. The Moon is falling toward Earth. It just keeps missing because it's also moving sideways fast enough that the curve of its fall matches the curve of the Earth. The same gravity that pulls the apple straight down pulls the Moon — but the Moon's sideways speed turns the fall into an orbit.
The equation: F = G × m₁ × m₂ / r². Two masses attract each other with a force that depends on both masses (more mass, more pull) and on the inverse square of the distance (twice the distance, one-quarter the pull). Every mass attracts every other mass, everywhere in the universe.
Why this is one of the most powerful frame moves in history
It said: the rules on Earth and the rules in the heavens are the same rules. The split was a human frame, not a natural one. Once that frame fell, all of celestial mechanics became calculable from the same equations as terrestrial mechanics. Within a century, the theory predicted the existence of Neptune (perturbations in Uranus's orbit revealed an unseen planet) and Halley's comet's return.
This is the frame-shift from track 1 in concrete form. The viewpoint of Earth as a special place with special rules dissolved into Earth as one mass among many, obeying universal rules.
What gravity isn't (yet)
Newton wrote the equation. He couldn't say why mass attracts mass. He famously refused to speculate (hypotheses non fingo — "I do not invent hypotheses"). The mechanism was unknown, the description was complete enough for predictions, and that was enough to do real science.
Two centuries later, Einstein gave a deeper answer: gravity isn't a force; it's the curvature of spacetime caused by mass. Apples fall because they follow the straightest possible path through curved spacetime, and curved spacetime, near a massive object, curves toward that object. We get to that picture in the next track (scale).
Newton's gravity is the engine bound. It works for everything where speeds are nowhere near light, gravity is nowhere near a black hole, and scales are nowhere near atomic. That covers cannonballs, planets, tides, satellites, and bridges — virtually all engineering. The bound is real, but the engine is enormous.