The pure region of the spheres, “il paese sincero,” is immortal as the spirits themselves;[617] but below the lowest celestial sphere (“la celestial c’ha men salita” Par. iv. 39) all is mortal and transitory, as the Greeks and the Latin poets had said. This is expressed in the Letter to Can Grande, when Dante contrasts the spheres (cœlum) and the elements, and says: “illud incorruptibile, illa vero corruptibilia sunt.”[618] It is also implied in Virgil’s address to Beatrice:

It is only through the spiritual teaching which Beatrice symbolizes that the human race can rise above all that is comprised within the heaven of the smallest sphere. And it is taught by Beatrice herself when, in the heaven of Mercury, she discourses on the mysteries of the creation and redemption. The angels, the souls of men, and the spheres, were created directly by God, she says, and are therefore immortal, but the elements, water, fire, air, earth, and all things that are formed out of them, also the souls or living principles of all animals and plants, were created through intermediate instruments and are mortal. These intermediate instruments are the heavenly bodies. Pure or inchoate matter was created at the beginning by God, and a power infused into the stars to give it form.[620]

Dante follows the classics and agrees with his contemporaries in arranging the four elements in four spheres, which are below the celestial spheres. The sphere of Fire is immediately within that of the moon, below this comes Air, then Water, and lastly the solid sphere of Earth. The contrast between Fire which constantly tends to rise towards the moon, and Earth which sinks towards the centre of the universe, is a favourite thought with him;[621] and lightning striking the earth is described as fleeing its proper place.[622] Aristotle seems to have regarded the four elements as flowing into one another, so that these lowly spheres beneath the moon were not sharply divided, but his mediæval disciples, following the Greek idea to its logical conclusion, conceived them with boundaries as definite as those of the celestial spheres. “Exhalations” could pass from one to another, but each particle of every element tended always to revert to its own place, which was distinct from the others.

And here they encountered a serious difficulty. If the sphere of water is naturally higher than that of earth, how comes it that in one quarter of the globe land rises above the ocean? It was recognised as necessary that this should happen in some part of the world, in order for an opportunity to be given for the elements to combine and to form all those substances and all those living creatures, including man, for which this earth was prepared; it was also agreed that the celestial spheres were the agency by which the Creator had first chosen to “let the dry land appear,” and by which it was maintained above the ocean; but the exact nature of this force and the way in which it acted was a question sometimes discussed. Albertus Magnus was of opinion that the rays of the sun and the stars, which had more power in the temperate and tropic zones than in the arctic, had here dried up the ocean, and he quotes Albumassar’s statement that this proves the existence of land on the southern side of the equator also. Ristoro, on the other hand, believed that the waters had been drawn up and rolled back from the habitable earth, and he attributes the elevating force to the stars of the north, bringing in his favourite theory that in this hemisphere they are far more numerous, and the constellations, from their upright position, are far more powerful than in the south.

He compares this lifting force of the stars to the attractive power of a magnet over iron, and argues that it must be the waters which are drawn away from the earth, not the earth which is lifted above the water, because the starry influence in its downward course would meet first the sphere of water, and moreover it is lighter and easier to move than Earth. He also thinks that the presence of springs on mountain tops is to be explained by the fact that the ocean is preserved at a higher level, hence water percolating through the porous land, as through a sponge, is forced up to its utmost height.

It does not seem as if Dante had paid much attention to this problem when he was writing the Convivio, for although he calls the habitable part of the earth “the uncovered land,” “la terra discoperta” (Conv. III. v. 73), he speaks of Earth and ocean as if they formed a globe together, “Questa terra ... col mare è centro del cielo,”[623] in the manner of Alfraganus, “Inter sapientes convenit, terram unà cum aqua globosam esse.”[624] But if we may believe that Dante is the author of the Quæstio de Aqua et Terra—a belief shared by many experts—he became greatly interested in the problem later on. According to the introduction and the final colophon, he attended a discussion on the subject and joined in it himself, when in Mantua, and afterwards in Verona less than two years before his death he wrote and read in public a Latin treatise in which his arguments and conclusions are set forth.

He seems to have had in mind Ristoro’s book, and while refuting some of the conclusions agrees with others. As a thirteenth century scholar he admits, as a matter of course, that the centre of the earth is the centre of the Universe and the goal towards which all heavy things tend; that earth as the heaviest element ought to be everywhere nearest this centre, while water ought to occupy the nobler place above it, that is, nearer to the most noble sphere of all which envelops all the others (the Empyrean). He also reasons, in true Dantesque and true mediæval fashion that there must be some place in the universe where all the elements may meet and mingle so that all potential forms of matter may be realized; otherwise the Mover of heaven, in whom all these forms (Plato’s Ideas) actually exist, would fail to give complete expression to his goodness, which is impossible.[625]

The author of the Quæstio denies, however, that this was accomplished by the removal of part of the sphere of water from the underlying earth. The ocean cannot have been drawn away and heaped up, he says, for water would always flow down again, being fluid and naturally seeking its own level; nor can the sphere of water be eccentric to that of Earth so that the latter emerges from it in one part. The reason for this is interesting since it implies a curious and apparently novel theory of gravity. Aristotle’s theory was that all heavy things tend by a natural law towards the centre of the universe, and therefore necessarily range themselves in spheres round it; the writer might therefore have made short work of Water’s eccentric sphere by stating briefly that it could not exist; instead of this, however, he suggests a new law of gravity, apparently invented on the spur of the moment, according to which everything which has weight tends towards the centre of its own circumference. If then earth and water had two separate centres, they would fall naturally in different directions, or as he puts it “to different downs.” Yet we know that the law of gravity is the same for both, and therefore their spheres must be concentric. The centre of the universe must be also the centre of the sea.[626] It had apparently been urged (perhaps in the discussion at Mantua) that since water follows the moon in the tides, its sphere may also imitate hers in being eccentric, but although Dante takes for granted that a connection between moon and tides is proved (and indeed it had been noted by the Greeks),[627] he replies that imitation in one particular need not imply imitation in all. Again, if the sphere of earth emerged from the sphere of water in the way proposed, the outline of the emergent earth must be circular, instead of which it is that of a half-moon, or nearly so, its width from east to west being much greater than its length from north to south.

Dante has been blamed for assigning this shape to the emergent earth, but the comparison of Earth’s habitable quadrant with the illuminated quadrant of the moon is perfectly just, as we saw with Ristoro,[628] from whom Dante is perhaps quoting here. The qualifying “vel quasi”[629] is added because the truly habitable regions did not extend over the whole quadrant, but stopped short at the arctic circle.

The existence of springs on mountain tops is explained by the fact that water rises thither not in the form of water but of vapour. Another upholder of Ristoro’s theory that Water was rolled away from Earth seems to have brought forward as evidence that sailors can see distant land from the mast which is invisible from the deck, and that therefore it evidently lies below the ocean; but this is confuted by the true and well known explanation that it is the convex shape of the sea which hides the distant land. Our author adds to his other arguments, in the curiously casual way so characteristic of his age, the ordinary observation which would be the first to occur to us, and quite sufficient in itself, viz. that instead of seeing a great wall of ocean rising above our sea-coasts, we invariably see the coast rising above the sea.

His own idea is that though the sphere of Water in general rises above Earth, in one part of the northern hemisphere Earth has been drawn up above the ocean. Earth must be subject to an uplifting influence, as well as to the downward drag of gravity, just as man is susceptible to the influence of reason as well as to the sway of his lower passions. This uplifting influence is not inherent in Earth herself, an upward impulse would be contrary to her own nature; nor can it be in water, or air, or fire, since all these are homogeneous bodies, and their virtue is evenly distributed, so that they could not cause a local and partial effect. It must be therefore in one of the heavens, and it remains for us to enquire which.

It cannot be in the heaven of the moon, for in the moon herself resides whatever influence comes from her sphere;[630] and she goes as far south of the equator as she does north: therefore she would raise land beyond the equator as well as on this side, but this is not so.

Then follows a passage of which commentators can make nothing as it stands:—

“Nec valet dicere quod illa declinatio non potuit esse propter magis appropinquare terræ per excentricitatem; quia si hæc virtus elevandi fuisset in luna, (quum agentia propinquiora virtuosius operentur) magis elevasset ibi quam hic.”[631]

Mr. Wicksteed suggests reading “elevatio” instead of “declinatio,” and apparently deletes the “non,”[632] and Dr. Moore seems to read the same way,[633] for both agree in interpreting as follows:—the author is stating an argument that the elevation of land (in only one hemisphere) might be due to the moon’s coming nearer to Earth in one part of her orbit, owing to its eccentricity; to which he replies that if that were the cause the elevation would be greater in the south than here in the north, because the moon is nearer to the earth when she goes south.

This is supposed to imply a belief that the moon is always in perigee[634] when south of the equator, whereas the fact that her perigee revolves all round the zodiac was as well known to Ptolemy and Alfraganus as it is to modern astronomers. The interpretation therefore convicts the author of the Quæstio of so serious and inexplicable a blunder that these commentators find themselves obliged to consider it as evidence either that it was not written by Dante, or that his knowledge of astronomy was much less extensive than has been supposed. It is suggested that there may have been a popular fallacy in his time that the moon was like the sun in this respect—although to know that the sun has a perigee, and that it is situated in the south, requires some acquaintance with astronomy! However, Dr. Moore has searched Alfraganus and other works in vain to find a suggestion of this kind.

Yet an explanation and a source of this statement is not far to seek, and instead of proving ignorance it indicates that the author of the Quæstio knew his Alfraganus well. The passage is evidently slightly corrupt, but the clue to its meaning lies in the word “eccentricity.” In two other places of the Quæstio the moon’s eccentric “orbis” is alluded to,[635] but if we translate this as “orbit” we shall be introducing modern ideas which meant nothing to Dante or his contemporaries. According to Alfraganus and Ptolemy the moon’s orb or sphere[636] was eccentric, but this was not the main cause of her varying distance from Earth. It was the revolution of her epicycle round its centre C, which caused her to move continually from apogee M to perigee P; and as the whole epicycle was meanwhile revolving on the deferent round C, and these two periods were not quite equal, the moon was as often in the perigee of her epicycle when it was south as when it was north. But besides this, the deferent, being eccentric to Earth, had also a perigee and apogee; and Alfraganus says that the perigee of the eccentric is always in the south. “Saturnus, Jupiter, atque Mars eccentricorum suorum absidas summas et imas habent declinatas a zodiaco, illas ad boream, hasce ad austrum, secundum eandem semper deflexus mensuram: quedadmodum res in Luna obtinet.”[637]

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.

In all the Divine Comedy there is no more beautiful allegory than this. Man in the age of innocence, man to-day when purified from sin, is already partly in heaven, though he still walks the earth. And like many another allegory of Dante’s, it follows naturally from the science of his day. Aristotle had said that the upper air “flows in a circle, because it is drawn along with the circulation of the Whole,” and Aquinas:—

“Thus the air which exceeds the greatest altitude of the mountains flows round, but the air which is contained within the altitude of the mountains is impeded from this flow by the immoveable parts of Earth.”

Purg. xxviii. 103-108 is almost a poetical paraphrase of this:—

The whole body of the air, everywhere in the world, is turning with the First Revolution (the Primum Mobile), wherever it is not interrupted by any obstruction (of hills etc.); and as at this height the Mountain is altogether free and open to the pure air, this motion strikes the thick forest and makes it murmur.[650]

From this region of pure air, Dante rises with Beatrice through the sphere of Fire, into which already in a dream he had been rapt, on the first night in Purgatory, by the Eagle with golden feathers, when the burning heat of the dream-fire roused him from his sleep.[651] Now he feels no heat, but is amazed at the vast extent of light, greater than any river or lake ever seen on earth, and at the same moment he begins to hear the music of the eternal spheres,[652] for he is approaching the heaven of the moon.

In each one he hears it until the seventh is reached, but here, in pity for his mortal senses, which are not yet strong enough to bear so much divine beauty, not only does Beatrice forbear to smile, but the sweet symphonies of heaven are silent.[653]

Did Dante then, in spite of Aristotle, believe in the music of the spheres? Perhaps the fact that only the Commedia, of all his works, makes mention of it indicates that he only thought of it as a poetical fiction, an allegory? Yet it was fully believed in by many in his day, although opinions varied greatly as to what note each planet sang. The favourite idea among Greek and Latin writers seems to have been that the notes made up a musical scale, the lowest sphere sounding forth the lowest note, and the star sphere its octave; but others thought that only the seven planets took part in the harmony, corresponding with the seven strings of the lyre: the moon being at the shortest distance from Earth, was the shortest string and gave the highest note, Saturn was the longest and gave the deepest.

Our own Milton, when he prays, “Ring out, ye crystal spheres,” bids the Primum Mobile join in, as well as the star sphere:

And Shakespear lets every separate star swell the chorus:

In the same spirit, but more literally perhaps than these, are we to understand the music of Dante’s spheres, which accompanies the singing of the angels:—