These statements were quoted in the fourteenth and fifteenth centuries to support the growing belief that India could be reached in a short time by sailing round the coast of Africa. But the want of nautical instruments restrained seamen from undertaking a voyage which carried them beyond the sight of familiar coasts and beneath new constellations. It was extremely perilous for European navigators to attempt to sail to India before they had acquired a knowledge of the use of the mariner’s compass and of the astrolabe. The polarity of the magnet was known among oriental nations several centuries before the Christian era. The use of the magnetic needle for the guidance of vessels, however, did not become popular in Europe until as late as the fourteenth century.[87] The slowness with which its use grew into favor with European seamen is ascribable to the prevailing superstition which hung like a darkening cloud over the minds of the people. The strange conservatism of the age is well described in a letter written, as it seems, in the year 1258, by Brunetto Latini, a learned Italian, Dante’s tutor, to Guido Cavalcanti of Florence. Speaking of his visit to Roger Bacon, the English philosopher and monk, at Oxford, England, he says: “The Parliament being summoned to assemble at Oxford, I did not fail to see Friar Bacon as soon as I arrived, and [among other things] he showed me a black ugly stone, called a magnet, which has the surprising property of drawing iron to it; and upon which, if a needle be rubbed, and afterwards fastened to a straw, so that it shall swim upon water, the needle will instantly turn toward the pole-star; therefore, be the night ever so dark, so that neither moon nor star be visible, yet shall the mariner be able, by the help of the needle, to steer his vessel aright.[88] “This discovery, which appears useful in so great a degree to all who travel by sea, must remain concealed until other times, because no master-mariner dares to use it lest he should fall under a supposition of his being a magician; nor would even the sailors venture themselves out to sea under his command if he took with him an instrument which carries so great an appearance of being constructed under the influence of some infernal spirit. A time may come when these prejudices, which are of such great hindrance to researches into the secrets of nature, will probably be no more; and then it will be that mankind shall reap the benefit of the labors of such learned men as Friar Bacon, and do justice to that industry and intelligence for which he and they now meet with no other return than obloquy and reproach.”[89] About the beginning of the fourteenth century, Flavia Gioja of Amalfi, in Naples, devised what were then known as the eight points of the superficies—the four cardinal and the four intermediate points of the compass-card.[90] From this time forward the use of the magnet gradually found favor with European seamen.