_Sir Isaac Newton, Cicero, and Gravitation._--How is it that Sir Isaac
Newton has obtained so world-wide a renown for his discovery of the law
of gravitation, when the following passage in the _Tusculan
Disputations_ proves it to have been well known to Cicero?
"Qua omnia delata gravitate medium mundi locum semper
expetant."--See lib. v. cap. 24.