430 



NATURE 



[June 2, 192 1 



by anybody. Hell is a conical opening reaching 

 to the centre of the earth, where the devil dwells 

 at the apex of the cone (Fig. 2). Among theologians 

 this was generally accepted as the proper place for 

 him. Even three hundred years later, when the 

 motion or non-motion of the earth was the burn- 

 ing question of the day, the idea appeared very 

 shocking to many that a body having the devil 

 in the middle could be supposed to travel among 

 the heavenly bodies, which were moved by angels. 

 Purgatory is a large conical hill, rising out of 

 the vast ocean at a point diametrically opposite 

 to Jerusalem, the navel of the dry land. The 

 heavenly spheres, ten in number, surround the 

 earth, and they are repeatedly alluded to as being 

 solid. In each of the first seven spheres spirits, 

 though they have not their permanent abode 

 there, appear to Dante in order to illustrate the 

 gradually increasing glory which they have been 

 found worthy to enjoy, and to indicate their 

 former earthly characters, which had been chiefly 

 influenced by one of the seven planets. The 

 shadow of the eai«th reaches as far as the third 

 sphere, and the spirits seen in the spheres of the 

 moon. Mercury, and Venus have the lowest degree 

 of bliss in the Empyrean. 



The tenth sphere, the Empyrean, is the dwell- 

 ing of the Deity. It is motionless, because all 

 motion implies change and a desire for something 

 better. The ninth, or crystalline, sphere is the 

 prime mover, endowed with circular motion which 

 expresses its praise of the Creator, and by its 

 almost incomprehensible speed it shows the desire 

 of each part of it to be joined to the Empyrean. 

 The eighth sphere is that of the fixed stars ; it 

 has a very slow eastward motion of its own of 

 one degree in a hundred years (precession), and 

 transmits the daily rotation received from the 

 ninth sphere to all the lower spheres. Dante 

 seems, however, to have been somewhat uncertain 

 about the source of rotation : in one place in the 

 "Convivio" (ii., 15) he attributes both rotation 

 and precession to the eighth sphere, though he 

 immediately afterwards returns to his usual 

 theory; and in another place ("Convivio," ii., 6). 

 when speaking of Venus, he says that "whether 

 the daily movement comes from some intelligence 

 or from the onrush of the prime mover, God 

 knows, for it appears to me presumptuous to 

 decide." But these passages seem only to indi- 

 cate some momentary hesitation between the con- 

 flicting statements of his sources. In the same 

 way he is doubtful about the nature of the Milky 

 Way, whether it is composed of stars or of 

 vapour. He is particularly disturbed by the dif- 



ference between the "new" translation of Aris- 

 totle (by Thomas Aquinas, from Greek) and the 

 "old " one (by Michael Scot, from Arabic), but he 

 inclines to the statement of the latter, that it is a 

 multitude of stars. 



The nine revolving spheres are moved by the 

 three triads of angelic intelligences, the Seraphim 

 as the highest in rank directing the ninth sphere, 

 while the angels govern the lowest sphere, that 

 of the moon. The planets were supposed to move 

 in the plane of the ecliptic. There is no mention 

 of the motion being eccentric, though Dante must 

 have seen the account of the eccentric circles 

 given in Al Fargani's book. But these were in- 

 convenient things to believers in a system of 

 spheres, and were better ignored. On the other 

 hand, there are several allusions to epicycles ; thus 

 it is said in a paragraph in the "Convivio " (ii.. 4) 

 about Venus that on the circle of its sphere there 

 is a small sphere which astronomers call an epi- 

 cycle, " and though we say that there are ten 

 spheres, this number does not comprise them all." 



The last and lowest of the ten spheres is that of 

 the moon. While the motion of Saturn is the swift- 

 est, because this is most divine motion, that of 

 the moon is the slowest ("Paradiso," iii., 51). The 

 revolutions of all the nine spheres are therefore 

 from east to west as supposed by some of the 

 early Greek philosophers and by all the Arabian 

 believers in spheres. As to the nature of the 

 moon, and particularly of the surface-markings, 

 Dante, in the "Convivio" (ii., 14), adopts a 

 theory, due to Averroes, according to which the 

 spots are caused by the rarity of some parts of 

 the moon's body which do not reflect the sun's 

 rays well. But in the "Paradiso" (ii. and xxii.) 

 this is objected to, and the spots, which Dante, 

 looking from above, sees only on the side of the 

 moon nearest the earth, are said to be due to 

 the light differing in various places under the 

 influence of different angelic guides. 



From the highest heavens to the lowest depths 

 of the earth we find in Dante a faithful guide to 

 the scientific ideas as well as to many popular 

 prejudices of his time. Though the theory of 

 spheres was during his lifetime defeated in 

 France, an Italian may well be pardoned for not 

 recognising this, particularly when we remember 

 that even 200 years later two separate attempts 

 were made in Italy to set up scientific theories 

 of concentric spheres. To the student of the 

 history of science it is a never-failing source of 

 pleasure to find medieval cosmology so beauti- 

 fully illuminated in the writings of the great 

 Florentine poet. 



The Natural History 



/^^LASSICAL plant-names like Mr)8iK7] Troa or 

 ^ spina Arahica, designed to indicate origin, 

 do not always fulfil their object. Pliny's specific 



1 •' Sino-iranica. Chinese Contributions to the History 6f Civilization in 

 Ancient Iran, with special refrrence to the History of Cultivated Plants 

 and Products." By Berthold I-aufer. (Field Museum of Natural History 

 Publication 201 : Anthropological Series, vol. xv., No. 3.) Pp. iv+^^s. 

 (Chicago, igig.) 



NO. 2692, VOL. 107] 



of Cultivated Plants. ^ 



reference to milium intra hos decem. annos ex 

 India in Italiam invectum has not obviated debate 

 as to the home and the identity of his plant. 

 Many notices of ancient crops connote only local 

 cultivation. 



Renaissance naturalists connected their culti- 



