Sir Isaac Newton's discovery was the law of _universal_ gravitation,
viz. that the solar system is kept together by the gravity of the
heavenly bodies towards the sun. This was founded on _terrestrial_
gravitation, of which the falling apple _put him in mind_, applied first
to the moon, and then _universally_ to the universe. (See _Penny
Cyclopædia_, art. "Gravitation;" Biot, "Life of Newton," in the
_Biographie Universelle_; or the translation of it in the "Life of
Newton" in the _Library of Useful Knowledge_, p. 5.) This is very
different from Cicero's words; in which[5] (_sc._ the earth) all things
borne downwards by their weight ever seek to reach the middle point of
the universe, which is also the lowest point in the earth (qui est idem
infimus in rotundo).
[Footnote 5: Moser's text has _in qua_, &c. terra.]