Other basic problems with regard to matter and force filled the minds of the medieval schoolmen quite as they do those of the modern generations. For instance, they occupied themselves with the question of the indestructibility of matter, and also, strange as it may seem, with the conservation of energy. We have presumably learned so much by experimental demonstration and original observation in the physical sciences in the modern times, and especially during the precious nineteenth century, that any thinking of the medieval mind along these lines might, in the opinion of those who know nothing of what they speak, be at once set aside without further question as preposterous, or at best nugatory. The opinions of medieval scholars in these matters would be presumed, without more ado, to have been so entirely [{313}] speculative as to deserve no further attention. Nothing could well be farther from the truth than this. Nowhere will more marvelous anticipations of what is most modern in science be found than in some of these considerations of basic principles in the physical sciences.
For instance, Thomas Aquinas, usually known as St. Thomas, in a series of lectures given at the University of Paris toward the end of the third quarter of the thirteenth century, stated as the most important conclusion with regard to matter that "Nihil omnino in nihilum redigetur.--Nothing at all will ever be reduced to nothingness." By this, as is very evident from the context, he meant to say that matter would never be annihilated and could never be destroyed. It might be changed in various ways, but it could never go back into the nothingness from which it had been taken by the creative act. Annihilation was pronounced as not being a part of the scheme of things as far as the human mind could hope to fathom its meaning.
In this sentence, then, Thomas of Aquin was proclaiming the doctrine of the indestructibility of matter. It was not until well on in the nineteenth century that the chemists and physicists of modern times realized the truth of this great principle. The chemists had seen matter change its form in many ways, had seen it disappear apparently in the smoke of fire or evaporate under the influence of heat, but investigation proved that if care were taken in the collection of the gases that came off under these circumstances, of the ashes of combustion and of the residue of evaporation, all the original material that had been contained in the supposedly disappearing substance could be recovered, or at least [{314}] completely accounted for. The physicists on their part had realized this same truth, and finally there came the definite enunciation of the absolute indestructibility of matter. St. Thomas's conclusion, "Nothing at all will ever be reduced to nothingness," had anticipated this doctrine by nearly seven centuries. What happened in the nineteenth century was that there came an experimental demonstration of the truth of the principle. The principle itself, however, had been reached long before by the human mind, by speculative processes quite as inerrable in their way as the more modern method of investigation.
When St. Thomas used the aphorism, "Nothing at all will ever be reduced to nothingness," there was another signification that he attached to the words quite as clearly as that by which they expressed the indestructibility of matter. For him nihil or nothing meant neither matter nor form, that is, neither the material substance nor the energy which is contained in it. He meant, then, that no energy would ever be destroyed as well as no matter would ever be annihilated. He was teaching the conservation of energy as well as the indestructibility of matter. Here once more the experimental demonstration of the doctrine was delayed for over six centuries and a half. The truth itself, however, had been reached by this medieval master-mind, and was the subject of his teaching to the university students in Paris in the thirteenth century. These examples should, I think, serve to illustrate that the minds of medieval students were occupied with practically the same questions as those which are now taught to the university students of our day, and that the content of the teaching was identical with ours.
The scholars of the Middle Ages are usually said to have been profoundly ignorant as regards the shape of the earth, its size, and the number of its inhabitants, and to have cherished the queerest notions, when they really permitted themselves any ideas at all, as to the antipodes. This is very true if the ideas of the ignorant masses of the people and the second-rate authors and thinkers be taken as the standard of medieval thought. Unfortunately, such sources as these have only too often served as authorities for modern historians of education and modern essayists on the history of science. This state of affairs would painfully suggest the curiously inverted notion of the supposed ideas entertained with regard to science in our day, that would be obtained by some thirtieth century student, were he to judge our scientific opinions from some of the queer books written by pretentiously ignorant writers, who have pet scientific hobbies of their own and exploit them at the expense of a long-suffering world, if by some accident of fortune these books should be preserved and the really great contributions to science be either actually lost or lost to sight. It is from Albert the Great and such men, and not from their petty contemporaries, that the true spirit of the science of the age must be deduced. Albert's biographer said:
"He treats as fabulous the commonly-received idea, in which Venerable Bede had acquiesced, that the region of the earth south of the equator was uninhabitable, and considers, that from the equator to the South Pole, the earth was not only habitable, but in all probability actually inhabited, except directly at the poles, where he imagines the cold to be excessive. If there be any animals there, he says, they must have very thick skins to defend them from the rigor of the climate, and they are probably of a white color. The intensity of cold is, [{316}] however, tempered by the action of the sea. He describes the antipodes and the countries they comprise, and divides the climate of the earth into seven zones. He smiles with a scholar's freedom at the simplicity of those who suppose that persons living at the opposite region of the earth must fall off, an opinion that can only rise out of the grossest ignorance, 'for when we speak of the lower hemisphere, this must be understood merely as relatively to ourselves.'
"It is as a geographer that Albert's superiority to the writers of his own time chiefly appears. Bearing in mind the astonishing ignorance which then prevailed on this subject, it is truly admirable to find him correctly tracing the chief mountain chains of Europe, with the rivers which take their source in each; remarking on portions of coast which have in later times been submerged by the ocean, and islands which have been raised by volcanic action above the level of the sea; noticing the modification of climate caused by mountains, seas and forests, and the division of the human race, whose differences he ascribes to the effect upon them of the countries they inhabit. In speaking of the British Isles, he alludes to the commonly-received idea that another distant island called Thile, or Thule, existed far in the Western Ocean, uninhabitable by reason of its frightful climate, but which, he says, has perhaps not yet been visited by man."
In only needs to be said in addition to this, that Albert had more than a vague hint of the possible existence of land on the other side of the globe. He gives an elaborate demonstration of the sphericity of the earth, and it has been suggested by more than one scholar that his views on this subject led eventually to the discovery of America.
Humboldt, the distinguished German natural philosopher of the beginning of the nineteenth century, who was undoubtedly the most important figure in scientific thought in his own time, and whose own work was great enough to have an enduring influence even down to our [{317}] day, in spite of the immense progress made during the nineteenth century, has praised Albert's work very highly. Almost needless to say, Humboldt was possessed of a thorough critical faculty and had a very wide range of knowledge, so that he was in an eminently proper position to judge of Albert's work. He has summed up his appreciation briefly as follows:
"Albertus Magnus was equally active and influential in promoting the study of natural science and of the Aristotelian philosophy. His works contain some exceedingly acute remarks on the organic structure and physiology of plants. One of his works, bearing the title of 'Liber Cosmographicus de Natura Locorum,' is a species of physical geography. I have found in it considerations on the dependence of temperature concurrently on latitude and elevation, and on the effect of different angles of incidence of the sun's rays in heating the ground, which have excited my surprise."