This property of the magnet was known in Dante’s day, as well as its power of attracting iron, though only the latter had been known to Ptolemy and the classical world. Whether the discovery came from China, where it is said that some form of compass has been used since the second century A.D., or whether it had been discovered independently by Arab or Italian navigators, we do not know: but scholars and poets in the twelfth and early thirteenth centuries write of the “ugly brown stone” used by sailors to make an instrument that cannot lie. For a needle, rubbed by it and run through a straw, when floated on water turns so surely to “the star” that one need never doubt its guidance. Thus writes Guyot, the poet of Languedoc, about 1200:— “Un art font qui mentir ne puet, Par la vertu de la manete, Une pierre laide et brunete, Ou le fers volentiers se joint, Ont: si esgardent le droit point, Puis c’une aiguile i ont touchie, Et en un festu l’ont couchie, En l’eve la metent sanz plus, * * * * * Puis se torne la pointe toute Contre l’estoile si sanz doute, Que ja nas hom n’en doutera.” And thus Ristoro:— “L’angola, che guidi li marinari, chè per la virtu del cielo è tratta e rivolta alla stella la quale è chiamata tramontana.”[287] ------------------------------------------------------------------------ [287] “The needle which guides mariners, for by the virtue of the heavens it is attracted and turned towards that star which is called the North Star.” _Composizione del Mondo_, Bk. VII. part iv. ch. 2. ------------------------------------------------------------------------ Albertus Magnus speaks of it in the same way, as something well known to mariners. It seems strange to us how Dante and his contemporaries failed to see the importance of this discovery; Brunetto Latini, when the ugly stone was shown to him on his visit to Roger Bacon at Oxford, even professing to regard it as a mere toy, of no practical use. Dante discusses the number of the stars known to Ptolemy, and describes the last mad voyage of Ulysses, who saw all the stars of the other pole, while ours sank low on the ocean floor;[288] but he does not seem to guess that the new toy would make possible even longer voyages than these, and that in time the blank in his celestial globe would be filled. ------------------------------------------------------------------------ [288] _Inf._ xxvi. 127-129. ------------------------------------------------------------------------