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Before Isaac Newton could develop his theory of gravity, a whole lot else had to happen. The story starts with the first known written records of repeating celestial changes, recorded by the Ancient Babylonians in "The Astronomical Diaries." Those records of regularties eventually led to the empirical theory of the motions of the planets put foward by Johannes Kepler, which Newton built upon to create his predictive theory of gravity. Both Kepler and Newton's theories make accurate predictions, but only Newton's, where gravity is described as a "force" proportional to the inverse squre of the separation of two masses, is fully generalizable. You can read all about it in The Path to Newton "book" (40+ page open Google Doc). Additionally, we have been collecting links to digitized manuscripts, original copies, and translations of the seminal texts in the Path (which is an on-going project!).
For more information about the Path to Newton and the pedagogy behind it, check out Professor Goodman's iPoster session from the 2019 American Astronomical Society conference.
A high-resolution version of the current "Path to Newton: chart is online, and can be printed on fabric upon email request to Professor Goodman: firstname.lastname@example.org