Dante and the early astronomers

by M. A. Orr

The upper and lower apsides are defined in chapter xii. as the positions of apogee and perigee respectively.[638]

In this quotation the word “declinatas” also supplies us with the meaning of Dante’s “declinatio,” which need not be changed for “elevatio.” He is using it in the astronomical sense of position north or south, like Alfraganus and modern astronomers, and it refers here to the “declinet” of five lines earlier. “Luna ... tantum declinet per zodiacum ab æquinoctiali versus polum antarcticum quantum versus arcticum.”[639]

It is only necessary to delete “quod” and “non potuit,” and the whole passage becomes clear and, from the point of view of mediæval astronomy, correct. The author has shown that the moon cannot be supposed to exert any preponderating influence in the northern hemisphere, because her declination south is equal to that in the north. Nor is it of any use, he adds, to say that this declination (south) results from her approaching the earth more nearly on her eccentric orb ([see diagram]);[640] for (although this does imply an unequal influence) if the elevating influence came from the moon, it would act more powerfully in the south than here in the north, since the nearer an agent is the more powerfully it acts.

He goes on to say that the same reasoning rules out the planetary spheres, and here Alfraganus still supports him, for Saturn, Jupiter, and Mars are said to have the perigees of their eccentrics in the south, just like the moon, while those of Venus and Mercury are continually changing.[641]

As for the Primum Mobile, or ninth sphere, it is uniform throughout, and consequently quite uniform in virtue, therefore there is no reason why it should elevate land here rather than elsewhere. Since, then, there are no more moving bodies except the star sphere, or eighth heaven, it must be from this that the lifting power proceeds. And it is specially adapted to exercise such an influence since it contains a number of stars, all of which have different “virtues.” Without repeating Ristoro’s naïve assertions about the greater number and the upright positions of the northern constellations, our author bids us remark that star differs from star, constellation from constellation, and that their influences are also diverse, so that those in the north have different virtues from those in the south. The lifting virtue which raises the land must reside in those stars which are between the equator and 67° north, since those are above the habitable earth; but we do not know the nature of the force they exercise, whether it attracts the land as a magnet attracts iron, or forces it up by generating underground vapours, such as have raised some mountains (Aristotle had said in his Meteorologica that volcanic hills were formed by pent-up winds beneath them).

After so elaborate a search for a power capable of raising land only in the north and not in the south, we naturally inquire why in the east and not in the west? But to this we only receive the reply that there was not enough material to go round, and that we must not ask presumptuous questions. Let us seek to approach divine and immortal things as nearly as is possible to human nature, but leave those which are too high for us.

This somewhat lengthy description of the contents of the Quæstio has been given because, even if it is not Dante’s work, it illustrates well the current ideas concerning the Cosmos, its form and forces. So many of the ideas, however, and even the expressions find parallels in the unquestioned writings of Dante, that the internal evidence for its genuineness is strong.[642]

In his poems Dante is faithful to his own descriptions of the universe in prose, and in the visionary journey of the Divine Comedy he passes successively through all the spheres which are enumerated in the Convivio and the Quæstio. The central sphere of earth, the lowest of all the elements, “il suggetto dei vostri elementi,”[643] is completely traversed, from side to side, and on the further side is seen the vast sphere of ocean which envelopes three-quarters of the earth. The Mountain which the poet has placed here (his only innovation) rises out of the water towards the heavens higher than any other, “inverso il ciel più alto si dislaga,”[644] and in climbing it he reaches that region in the sphere of air into which no cold exhalations can rise from earth or sea, neither the “secco vapor”[645] which causes wind and earthquake, nor the “esalazion dell’ aqua”[646] from which are formed rain and hail, cloud and dew. Hot exhalations ascend to the sphere of fire, there to become meteors or comets ([see p. 103]); but the cold vapours rising as high as they can towards the sun which draws them up (“retro il calor”[647]), are unable to ascend beyond the Gate of Purgatory.[648] Therefore Purgatory is exempt from all changes except those caused by that which heaven receives from itself into itself. This was ingeniously conjectured by Venturi to be light, since there is change of day and night in Purgatory; but from the context it seems clear that human souls are meant. Souls come forth from their Creator, whose special abode is the heaven of heavens, and return thither after purification. And it was the rising of the purified soul of Statius, ready to return to heaven, which had been the cause of that trembling of the Mountain of which he is here speaking.

After learning this, Dante is surprised to find, on the summit of the Mountain, that his brows are caressed by a gentle breeze which comes from the east and bends all the trees of the Forest in one direction. Matilda tells him that it is true no atmospheric changes are felt on this Mountain, and it was for this that it was made to rise so high, so that man in the Garden of Eden, on the top of the Mountain, should be untroubled by the disturbances which occur lower down: what he feels now is no fluctuating wind. On this lofty mountain, remote from any other land in the midst of the hemisphere of sea, he feels for the first time the revolution of the atmosphere uninterruptedly following the movement of the celestial spheres.

The idea that Eden was on a lofty mountain, secure from stormy weather, and inaccessible to fallen man, was a familiar one with mediæval writers: it was sometimes located on Adam’s Peak in Ceylon, and Bede thought it might rise as high as the moon, but Albertus Magnus says this was only meant figuratively. But the connection with Purgatory, and the thought that here the movement of the heavens might be felt as a soft breeze, is, so far as I know, all Dante’s own.