no manner of perturbation in ſo many ages from the actions of the conflicting matter. Certainly if theſe fictitious motions are more compounded and more hard to be accounted for than the true motions of the Planets and Comets, it ſeems to no purpoſe to admit them into philoſophy; ſince every cauſe ought to be more ſimple than its effects. Allowing men to indulge their own fancies, ſuppose any man ſhould affirm that the Planets and Comets are ſurrounded with atmoſpheres like our Earth; which hypotheſis ſeems more reaſonable than that of vortices. Let him then affirm that theſe atmoſpheres by their own nature move about the Sun and deſcribe conic ſections, which motion is much more eaſily conceived than that of the vortices penetrating each other. Laſtly, that the Planets and Comets are carried about the Sun by theſe atmoſpheres of theirs; and then applaud his own ſagacity in diſcovering the cauſes of the celeſtial motions. He that rejects this fable muſt alſo reject the other; for two drops of water are not more like than this hypotheſis of atmoſpheres, and that of vortices.
Galileo has ſhewn, that when a ſtone projected moves in a parabola, its deflexion into that curve from its rectilinear path is occaſioned by the gravity of the ſtone towards the Earth, that is, by an occult quality. But now ſome body, more cunning than he, may come to explain the cauſe after this manner. He will ſuppofe a certain ſubtile matter, not diſcernable by our ſight, our touch or any other of our ſenſes, which fills the ſpaces which are near and contiguous to the ſuperficies of the Earth; and that this matter is carried with different directions,
and various, and often contrary, motions, deſcribing
