[1] In connection with this discussion it is to be remembered that nearly two centuries were required for the Copernican system, promulgated in 1543, in the De orbium coelestium revolutionibus, to become generally popularized; and that in 1633, only sixteen years before the Voyage to the Moon was written, Galileo had been compelled by the Inquisition to deny the motion of the earth.
[2] According to the Ptolemaic system, still generally accepted by "modern Philosophers" at the time of Cyrano's writing, the fixed stars, the sun, the moon, and each of the five (then known) planets, revolved about the earth in different orbits, according to various "epicycles" and "excentrics."
[3] The motion of the moon, for instance, was explained in the Ptolemaic system as an epicycle carried by an excentric; the centre of the excentric moving about the earth in a direction opposite to that of the epicycle.
[4] The French has: "of the two other motions": i.e., the movement of the fixed stars, and that of the planets.
[5] Gassendus or Gassendi was Cyrano's own teacher of Philosophy. Of Provençal origin, and at first Professor in the University of Aix, he came to Paris in 1641, and gave both private lessons and public courses as Professor of the Collège Royal. It was in one of his private classes that Cyrano was a fellow-student with Chapelle, Hesnaut, Bernier, and almost certainly Molière; the most important group of young "libertins" (i.e. free-thinkers) of the epoch.
Gassendi was a bitter opponent of the supposedly Aristotelian school-philosophy of the time; and was on the whole the leader of those who in the seventeenth century followed Epicurean methods in thought. He is the author of a life of Epicurus, and an exposition of his philosophy. He was also an opponent of Descartes, being the most important contemporary supporter of empiricism as against the essentially idealistic method of Descartes.
He is important also as a popularizer of the Copernican system, by his Life of Copernicus, and his Institutio Astronomica (1647).
[6] A dog trained to turn a spit, by running about in a rotary cage attached to it. The French has simply: "as a dog makes a wheel turn, when he runs about in it."
[7] Cyrano had probably learned this from his master Gassendi. Cf. his "Epistola XX. de apparente magnitudine solis," 1641. Modern Gassendis say the sun is 1,300,000 times greater than the earth in volume, 316,000 times in mass.