The philosophy of Descartes was predominant throughout Europe. Appealing to the imagination, and not to the reason, of mankind it was quickly received into popular favor, and the same causes which facilitated its introduction, extended its influence and completed its dominion over the human mind. In explaining all the movements of the heavenly bodies by a system of vortices in a fluid medium diffused through the universe Descartes had seized upon an analogy of the most alluring and deceitful kind. Those who had seen heavy bodies revolving in the eddies of a whirlpool or in the gyrations of a vessel of water thrown into a circular motion had no difficulty in conceiving how the planets might revolve round the sun by an analogous movement. The mind instantly grasped at an explanation of so palpable a character and which required for its development neither the exercise of patient thought nor the aid of mathematical skill. The talent and perspicuity with which the Cartesian system was expounded, and the show by which it was sustained, contributed powerfully to its adoption, while it derived a still higher sanction from the excellent character and the unaffected piety of its author. Thus intrenched, as the Cartesian system was, in the strongholds of the human mind, and fortified by its most obstinate prejudices, it was not to be wondered at that the pure and sublime doctrines of the _Principia_, were distrustfully received and perseveringly resisted. The uninstructed mind could not readily admit the idea that the great masses of the planets were suspended in empty space and retained in their orbits by an invisible influence residing in the sun; and even those philosophers who had been accustomed to the rigor of true scientific research, and who possessed sufficient mathematical skill for the examination of the Newtonian doctrines, viewed them at first as reviving the occult qualities of the ancient physics, and resisted their introduction with a pertinacity which it is not easy to explain.