Philosophical Dictionary, by Voltaire


How is it that the axis of the earth is not perpendicular to the equator? Why is it raised toward the north and inclined towards the south pole, in a position which does not appear natural, and which seems the consequence of some derangement, or the result of a period of a prodigious number of years?

Is it true that the ecliptic continually inclines by an insensible movement towards the equator and that the angle formed by these two lines has a little diminished in two thousand years?

Is it true that the ecliptic has been formerly perpendicular to the equator, that the Egyptians have said so, and that Herodotus has related it? This motion of the ecliptic would form a period of about two millions of years. It is not that which astounds us, for the axis of the earth has an imperceptible movement in about twenty-six thousand years which occasions the precession of the equinoxes. It is as easy for nature to produce a rotation of twenty thousand as of two hundred and sixty ages.

We are deceived when we are told that the Egyptians had, according to Herodotus, a tradition that the ecliptic had been formerly perpendicular to the equator. The tradition of which Herodotus speaks has no relation to the coincidence of the equinoctial and ecliptic lines; that is quite another affair.

The pretended scholars of Egypt said that the sun in the space of eleven thousand years had set twice in the east and risen twice in the west. When the equator and the ecliptic coincided, and when the days were everywhere equal to the nights the sun did not on that account change its setting and rising, but the earth turned on its axis from west to east, as at this day. This idea of making the sun set in the east is a chimera only worthy of the brains of the priests of Egypt and shows the profound ignorance of those jugglers who have had so much reputation. The tale should be classed with those of the satyrs who sang and danced in the train of Osiris; with the little boys whom they would not feed till after they had run eight leagues, to teach them to conquer the world; with the two children who cried bec in asking for bread and who by that means discovered that the Phrygian was the original language; with King Psammeticus, who gave his daughter to a thief who had dexterously stolen his money, etc.

Ancient history, ancient astronomy, ancient physics, ancient medicine (up to Hippocrates), ancient geography, ancient metaphysics, all are nothing but ancient absurdities which ought to make us feel the happiness of being born in later times.

There is, no doubt, more truth in two pages of the French Encyclopædia in relation to physics than in all the library of Alexandria, the loss of which is so much regretted.

Last updated Tuesday, March 4, 2014 at 18:25