tion of natural phenomena. Newton "was the first ever to figure out that these two phenomena [moon's earth orbit; ordinary gravity of falling objects on earth] were due to the same force" (p. 69). Elsewhere Sagan continues:
Kepler and Newton represent a critical transition in human history, the discovery that fairly simple mathematical laws pervade all of Nature; that the same rules apply on Earth as in the skys; and that there is a resonance between the way we think and the way the world works. They unflinchingly respected the accuracy of observational data, and their predictions of the motion of the planets to high precision provided compelling evidence that, at an unexpectedly deep level, humans can understand the Cosmos (p. 71).
Just as in the medieval world all the universe was in harmony, so it became in the Ptolemaic, post-medieval, pre-Enlightenment world, and so it was to become in the Newtonian universe. The difference appears to have been that God was the source of symmetry and explanation in the earlier period, while fundamental laws
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