H. Butterfield on the Structure of the Medieval Universe

 

An introductory sketch of the medieval view of the cosmos must be qualified first of all with the reservation that in this particular realm of thought there were variations, uncertainties, controversies and developments which it would obviously be impossible to describe in detail. On the whole, therefore, it would be well, perhaps, if we were to take Dante’s view of the universe as a pattern, because it will be easy to note in parenthesis some of the important variations that occurred, and at the same time this policy will enable us to see in a single survey the range of the multiple objections which it took the Copernican theory something like a hundred and fifty years to surmount.

 

According to Dante, what one must have in mind is a series of spheres, one inside another, and at the heart of the whole system lies the motionless earth. The realm of what we should call ordinary matter is confined to the earth and its neighborhood -- the region below the moon; and this matter, the stuff that we can hold between our fingers and which our modern physical sciences set out to study, is humble and unstable, being subject to change and decay for reasons which we shall examine later. The skies and the heavenly bodies -- the rotating spheres and the stars and planets that are attached to them -- are made of a very tangible kind of matter too, though it is more subtle in quality and it is not subject to change and corruption. It is not subject to the physical laws that govern the more earthy kind of material which we have below the moon. From the point of view of what we should call purely physical science, the earth and the skies therefore were cut off from one another and, for a medieval student, were separate organizations, though in a wider system of thought they dovetailed together to form one coherent cosmos.

 

As to the ordinary matter of which the earth is composed, it is formed of four elements, and these are graded according to their virtue, their nobility. There is earth, which is the meanest stuff of all, then water, then air and, finally, fire, and this last comes highest in the hierarchy. We do not see these elements in their pure and undiluted form, however -- the earthy stuff that we handle when we pick up a little soil is mixed with earthiness. Of the four elements, earth and water posses gravity; they have a tendency to fall; they can only be at rest at the center of the universe. Fire and air do not have gravity, but possess the very reverse; they are characterized by levity, an actual tendency to rise, though the atmosphere clings a little to the earth because it is loaded with base mundane impurities. For all the elements have their spheres, and aspire to reach their proper sphere, where they find stability and rest; and when flame, for example, has soared to its own upper region it will be happy and contented, for here it can be still and can most endure.

 

If the elements did not mix -- if they were all at home in their proper spheres -- we should have a solid sphere of earth at the heart of everything and every particle of it would be still. We should then have an ocean covering that whole globe, like a cap that fitted all round, then a sphere of air, which far above mountaintops was supposed to swirl round from east to west in sympathy with the movement of the skies. Finally, there would come the region of enduring fire, fitting like a sphere over all the rest.

 

That, however, would be a dead universe. In fact, it was a corollary of this whole view of the world that ordinary motion up of down or in a straight line could only take place if there was something wrong -- something displaced from its proper sphere. It mattered very much, therefore, that the various elements were not all in order but were mixed and out of place -- for instance, some of the land had been drawn out above the waters, raised out of its proper sphere at the bottom, to provide habitable ground. On this land natural objects existed and, since they were mixtures, they might, for example, contain water, which as soon as it was released would tend to seek its way down to the sea. On the other hand, they might contain the element of fire, which would come out of them when they burned and would flutter and push its way upwards, aspiring to reach its true home. But the elements are not always able to follow their nature in this pure fashion -- occasionally the fire may strike downwards, as in lightning, or the water may rise in the form of vapor to prepare a store of rain. On one point, however, the law was fixed: while the elements are out of their proper spheres they are bound to be unstable -- there cannot possibly be restfulness and peace. Woven, as we find them, on the surface of the globe, they make a mixed and chancy world, a world that is subject to constant mutation, liable to dissolution and decay.

 

It is only in the northern hemisphere that land emerges, protruding about the waters that cover the rest of the globe. This land has been pulled up, out of its proper sphere, says Dante -- drawn not by the moon or the planets or the ninth sky, but by an influence from the fixed stars, in his opinion. The land stretches from the Pillars of Hercules in the west to the Ganges in the east, from the Equator in the south to the Arctic Circle in the north. And in the center of this whole habitable world is Jerusalem, the Holy City. Dante had heard stories of travellers who had found a great deal more of the continent of Africa, found actual land much further south than he had been taught to consider possible. As a true rationalist he seems to have rejected "fables" that contradicted the natural science of his time, remembering that travellers were apt to be liars. The disproportionate amount of water in the world and the unbalanced distribution of the land led to some discussion of the whereabouts of the earth's real centre. The great discoveries, however, culminating in the unmistakable discovery of America, provoked certain changes in ideas, as well as a debate concerning the possibility of the existence of inhabited countries at the antipodes. There was a growing view that earth and water, instead of coming in two separate circles, the one above the other, really dovetailed into one another to form a single sphere.

 

All this concerns the sublunary region; but there is another realm of matter to be considered, and this, as we have already seen, comes under a different polity. The skies are not liable to change and decay, for they -- with the sun, the stars and the planets -- are formed of a fifth element, an incorruptible kind of matter, which is subject to a different set of what we should call physical laws. If earth tends to fall to the centre of the universe, and fire tends to rise to its proper sphere above the air itself, the incorruptible stuff that forms the heavens has no reason for discontent -- it is fixed in its congenial place already. Only one motion is possible for it -- namely, circular motion -- it must turn while remaining in the same place. According to Dante there are ten skies, only the last of them, the Empyrean Heaven, the abode of God, being at rest. Each of the skies is a sphere that surrounds the globe of the earth, and though all these spheres are transparent they are sufficiently tangible and real to carry one or more of the heavenly bodies round on their backs as they rotate about the earth -- the whole system forming a set of transparent spheres, one around the other, with the hard earth at the centre of all. The sphere nearest to the earth has the moon attached to it, the others carry the planets or the sun, until we reach the eighth, to which all the fixed stars are fastened. A ninth sphere has no planet or star attached to it, nothing to give visible signs of its existence; but it must be there, for it is the primum mobile -- it turns not only itself but all the other spheres or skies as well, from east to west, so that once in twenty-four hours the whole celestial system wheels round the motionless earth. This ninth sphere moves more quickly than any of the others, for the spirits which move it have every reason to be ardent. They are next to the Empyrean Heaven.

 

In the system of Aristotle the spheres were supposed to be formed of a very subtle ethereal substance, moving more softly than liquids and without any friction; but with the passage of time the idea seems to have become coarsened and vulgarized. The successive heavens turned into glassy or crystalline globes, solid but still transparent, so that it became harder for men to keep in mind the fact that they were frictionless and free from weight, though the Aristotelian theory in regard to these points was still formally held.

 

-- The Origins of Modern Science, 1300-1800, revised ed. (New York: Free Press 1965), 29-33