Theophrastus and Pliny speak of this native magnet as possessing, like amber, the property of attracting straw, dried leaves, bark and other light bodies. The different sorts of loadstones, of which the best were blue in colour (as stated by Taisnier, Porta, Barthol. de Glanville and others), are thus alluded to by Pliny (“Nat. Hist.,” lib. xxxvi. cap. 16): “Sotacus describes five kinds: the Æthiopian; that of Magnesia, a country which borders on Macedonia; a third from Hyettus, in Boetia; a fourth from Alexandria, in Troas; and a fifth from Magnesia, in Asia” (Porta, “Natural Magick,” Book VII. chap. i.). He further says that iron cannot resist it; “the moment the metal approaches it, it springs toward the magnet, and, as it clasps it, is held fast in the magnet’s embrace.” It is by many called _ferrum vivum_, or quick iron.[6] Claudian speaks of it as “a stone which is preferred to all that is most precious in the East.... Iron gives it life and nourishes it” (Claudian, Idyl V; Ennemoser, “Hist. of Magic,” Vol. II. p. 27). Hippocrates, the father of medical science, calls it “the stone which carries away iron.” Epicurus, an Athenian of the Ægean tribe, says: “The _loadstone or magnet_ attracts iron, because the particles which are continually flowing from it, as from all bodies, have such a peculiar fitness in form to those which flow from iron that, upon collision, they easily unite.... The mutual attraction of _amber_ and like bodies may be explained in the same manner.” Hier. Cardan intimates that “it is a certain appetite or desire of nutriment that makes the loadstone snatch the iron....” (“De Subtilitate,” Basileæ, 1611, lib. vii. p. 381). Diogenes of Apollonia (lib. ii. “Nat. Quæst.,” cap. xxiii.) says that “there is humidity in iron which the dryness of the magnet feeds upon.” Cornelius Gemma supposed invisible lines to stretch from the magnet to the attracted body, a conception which, says Prof. Tyndall, reminds us of Faraday’s lines of force. Lucretius accounts for the adhesion of the steel to the loadstone by saying that on the surface of the magnet there are hooks, and, on the surface of the steel, little rings which the hooks catch hold of. Thales, Aristotle, Anaxagoras of Clazomenæ and the Greek sophist Hippias, ascribe the loadstone’s attractive virtue to the _soul_ with which they say it is endowed. Humboldt (“Cosmos,” article on the Magnetic Needle) says _soul_ signifies here “the inner principle of the moving agent,” and he adds in a footnote: “Aristotle (“De Anima,” I. 2) speaks only of the animation of the magnet as of an opinion that originated with Thales.” Diogenes Laertius interprets this statement as applying also distinctly to amber, for he says: “Aristotle and Hippias maintain as to the doctrine enounced by Thales.” The native magnet appears to have long been known in nearly every quarter of the globe (Humboldt, “Cosmos,” 1848, Vol. V., and Harris, “Rudimentary Magnetism,” Parts I and II).