Note 32 — Chapter I · INTRODUCTORY

‘It might almost be supposed that the following lines were written by one of our own contemporaries: they are, however, extracted from a chapter of Avicenna on the origin of mountains. This author was born in the tenth century. Mountains may be due to two causes. Either they are effects of upheavals of the crust of the earth, such as might occur during a violent earthquake, or they are the effect of water, which, cutting for itself a new route, has denuded the valleys, the strata being of different kinds, some soft, some hard. The winds and waters disintegrate the one, but leave the other intact. Most of the eminences of the earth have had this latter origin. It would require a long period of time for all such changes to be accomplished, during which the mountains themselves might be somewhat diminished in size. But that water has been the main cause of these effects is proved by the existence of fossil remains of aquatic and other animals on many mountains’ (The Intellectual Development of Europe, Draper, I. 410). Gassendi at least affects a knowledge of Avicenna, and frequently refers to him.