COPERNICUS IN ITALY. 



401 



earth to be more or less displaced from the cen- 

 tral point of their orbits; while the planetary 

 " stations and retrogradations " were met by the 

 theory of epicycles, or smaller spheres rotating 

 on the circumference of each great sphere, which 

 caught the planets in their revolution, and whirled 

 them back over a, portion of the paths already 

 traversed. This ingenious system, adopted by 

 Hipparchus, and fortified by the irresistible au- 

 thority of Ptolemy, formed the basis of the only 

 compact body of science, except geometry, or- 

 ganized by the labors of antiquity. It derived 

 the almost impregnable strength of its position 

 from this — that it was intrenched behind a mass 

 of observations and calculations which had a 

 false air of scientific truth. It explained phe- 

 nomena in detail, although it outraged reason in 

 principle. The fascinating superstitions of as- 

 trology, which were closely dependent on it, 

 helped to give it efficacy and duration ; for error 

 is persistent, though truth be invincible. 



A people fresh from the reveries of the desert, 

 whose thirst for knowledge was only equaled by 

 their thirst for conquest, collected the inheritance 

 of the school of Alexandria, and transmitted it to 

 Western Europe. " Efface the Arabs from his- 

 tory," says Libri, 1 " and the renaissance of letters 

 in Europe will be delayed for several centuries." 

 And, in fact, the works of Aristotle, Euclid, and 

 Ptolemy, were, until the fifteenth century, only 

 known in Italy by means of translations from the 

 Arabic ; while, during great part of the middle 

 ages, Moorish universities were the centres of 

 culture, and Moorish geometers and astronomers 

 the arbiters of science in Europe. But as the 

 genius of the Arabs was decorative rather than 

 creative, so their intellect was ingenious rather 

 than inventive. With all their laborious patience 

 as commentators, and subtilty as interpreters, 

 the Arabs laid down no new line of thought, and 

 evolved no new truths out of the old materials. 

 Thus knowledge made no siugle step forward 

 during the many centuries in which they were 

 its custodians. The " Almagest," as they called 

 Ptolemy's "Syntax of Astronomy" (from al, the 

 Arabic article, combined with fieyicrros, greatest), 

 was their astronomical Koran, and Ptolemy was to 

 them as exclusively the astronomer as Mohammed 

 was (he Prophet. It was not until the revival of 

 letters in Italy enabled Christian Europe to form 

 an independent judgment, that the imposing pres- 

 tige of Ptolemy and his Arab commentators be- 

 gan gradually to decline. It was found possible 

 to conceive a constitution of the universe differ- 

 1 "Histoire des Sciences Mathematiques," vol. i., p. 151. 



26 



ent from that consecrated by the authority of the 

 Alexandrian philosopher, when other ideas were 

 found to have been entertained by sages of equal 

 learning and a more venerable antiquity. 



It was not, however, among astronomers by 

 profession that innovating opinions began to 

 spread during the fifteenth century; the preju- 

 dices as well as the interests of their caste were 

 opposed to change. Purbach and Regiomonta- 

 nus were as orthodox Ptolemaists as Isaac Aben 

 Sid or Abdurrahman Suphi. The very complica- 

 tions of the system made it dear to those whose 

 lives had been devoted to mastering its intricate 

 details, since we value most what we have ac- 

 quired with the greatest difficult)', and our past 

 labor becomes an intimate part of our present 

 self-love. The theory of the earth's rotation was 

 adopted by many lay thinkers on the subject be- 

 fore a single expert had declared in its favor, and 

 Celio Calcagnini, the notary of Ferrara, spoke of 

 the contrary opinion as an error manifest to all 

 thoughtful men, long before Magini, the Bologn- 

 ese astronomer, composed his twelve books on 

 the " Primum Mobile." 



The first of these astronomical heretics was a 

 German by birth, but an Italian by culture, a 

 metaphysical cardinal and theologian, a dilettante 

 in science, and one of the earliest of modern Pla- 

 tonic philosophers. Nicholas Krebs was the son 

 of a poor fisherman, and was born in 1401, at 

 Cues, on the banks of the Moselle. His remark- 

 able talents procured for him the advantage of 

 an education at the University of Padua, and af- 

 terward raised him to the highest honors of the 

 Church. His philosophical writings received much 

 attention from the Italian prelates assembled at 

 the Council of Basle, in the stormy discussions of 

 which he took a prominent part; and his name 

 would no doubt have become more widely famous 

 had not a premature death cut short his career 

 at the comparatively early age of forty-seven. 

 His ideas as to the constitution of the universe 

 are contained in the singular treatise, " De Docta 

 Ignorantia." They are founded on metaphysical 

 rather than on scientific considerations, the con- 

 ception of physical cause being as yet only dimly 

 present to the minds of men. By a modification 

 of the Platonic idea, Cardinal Cusa conceives the 

 universe as a vast organism, whose life is the 

 breath of God, having no material centre or cir- 

 cumference, but infinite as its Maker. He lays 

 down as an axiom that motion can only be appre- 

 hended by comparison with what is fixed, and 

 thence clearly deduces the motion of the earth : 

 " Ex his quidem manifestum est terrain moveri." 



