Science and Medieval Thought

The controversy lay between the Realists11 and the Nominalists; and the issues of it, in the eleventh century, – at which time the “Dark Ages” passed into the earlier of the two periods of the Middle Ages, – were formulated on the realist side by William of Champeaux, while the Breton Rousselin, or Roscellinus, had the perilous honour of defining them on behalf of the nominalists12. To see the depth of the difference we must step back a little, to a time when metaphysics and psychology were not distinguished from other spheres of science13, and all research had for its object the nature of being. Plato himself held ideas not as mere abstractions but in some degree as creative powers; and we shall see how potent this function became in the thought of the Middle Ages when, in the ardour of research into the nature of being, the modes of individuating principles were distinguished or contrasted with an ingenuity incomprehensible to Plato or Aristotle, or at any rate undesired by these greater thinkers. Aristotle avoided the question whether form or matter individuate; he held that there is no form and no matter extrinsic to the individual. But by the medieval realist every particular, every thing, was regarded as after some fashion the product of universal matter and individual form. Now “form” might be regarded, and severally was regarded, as a shaping, determinative force or principle, pattern type or mould, having real existence apart from stuff, or, on the other hand, as an abstract principle or pattern having no existence but as a conception of the mind of the observer. The realists roundly asserted that form is as actual as matter, and that things arise by their participation – without whiteness no white thing, without humanity no man; and not individuals only: for the realist, out-platonising Plato, genera and species also had their forms, either pre-existent (“universalia ante rem”), or continuously evolved in the several acts of creation (“universalia in re”). Indeed for the extreme realist every “predicamental modality” was “aliquid ens separatum”; for instance, the soul, the active intellect, the passive intellect, and so on: conversely, by fusing idea with will, for other philosophers realism would get pushed back into efficient reason or divine will, and almost vanish14. By this latter route the Sorbonne, originally opposed to the Thomists, became nominalist after all; as did those once pious realists the Augustinians and Cistercians. Setting aside then the extreme nominalists, who would have dissolved thought by declaring all creatures to be so individual as to be incomparable, – “pulverising existence into detached particulars,” as some one has put it – and that names of kinds are mere nouns, or indeed mere air (“flatus vocis”), the prevalent nominalists were content to deny to ideas, forms, principles, or abstractions any other existence than as functions of the human mind – as subjective conceptions. For Ockham, says Hauréau, an idea was but a modality of the thinking subject. Abstractions then for these thinkers were but mental machinery for analysis of the concrete. Aristotle was as obscure and inconsistent in his language herein, and often elsewhere, as he was profound and scrupulous; but when his works came to be studied as a whole, and in the original tongue, the influence of his method, rather than the close consistency of his language, told against realism: virtually he was a conceptualist, and he found reality, where Plato denied it, in the particular object of sense15.

Even Francis Bacon, who was deeply indebted to Aristotle, never extricated himself from the tangle of form, cause and law16.

Now this was a great argument, no empty dispute; the bones of dead controversies cumber the ground, but no controversy was empty which moved profoundly the minds and passions of men: both for ecclesiastical and secular thought the dispute was grave. While realism was essential to the Church – for instance, on realist grounds St Anselm defended the medieval doctrine of the Trinity against Roscellinus; the Church herself claimed a real existence apart from the wills of successive generations of individual and variable men; she taught that Man had fallen not only in many or all individual cases, but as a kind having a real existence17, and again that in the Mass there is change of hypostasis18– while then realism was essential to the Faith, yet if forms pre-exist (“ante rem”) then the acts of God must be predetermined – “fatis” non “avolsa voluntas”; or if forms are only “in re” God must be form, living in each and every act and thing, which is Pantheism (“materia omnium Deus”): an impersonal conception and a dissolution of dogma which the Church must and did abhor. “Pessimus error” – there is the abyss, cried Albert, avoiding it by dialectical juggles. Erigena, the brilliant prophet and protestant19 of the first period of the scholastic philosophy, was virtually a pantheist after the pattern of Parmenides20; as Spinoza was the last great realist. David of Dinan again was such a pantheist, though luckily for him the Church did not find it out till he was dead; and he was martyred only in his bones. Indeed the great Robert of Lincoln barely escaped the accusation of pantheism under the wing of Augustine. The heresies of David, and of Amaury, caused the reaction of the first years of the 13th century against Aristotle. Amaury seems indeed to have cleared out Christian dogma pretty thoroughly, and to have preached the coming of science as the “third age” of the world. Many of his followers were sent to the stake; by the Synod of Paris (1209) the works of Aristotle were proscribed, and many copies of them burned. This proscription was virtually withdrawn by Gregory the Ninth in 1231; and Hales, Albert and St Thomas devoted themselves again to the study of Aristotle, and established his supremacy21. Indispensable then as realism was for the Church, its creed, and its sacraments, yet therein it found itself in a dilemma between the conceptions of a Creator working under conditions, and of a spirit immanent in matter; and when theological philosophy culminated in St Thomas, and was fixed by him as it now rules in Rome, this difficulty was rather concealed in his system than resolved22. Every scheme of thought must make some declaration on the nature and place of universals; the problem was no hair splitting23, it dealt with the very nature and origin of being; it agitated the minds of thinking men at a time of the most fervid and widespread enthusiasm for knowledge which the Western world has ever known, – at a time when Oxford counted its students by thousands, and when in Paris a throng athirst for knowledge would stretch from the cloisters of the Mathurins to the faubourg of St Denis24; and, in respect of our theme of this day, we shall see that even Harvey was embarrassed by certain aspects of it.

For, to resume, closely allied to the argument concerning universals was that concerning “form and matter.” Whether the terms used were “form and matter,” force or energy or “pneuma” and matter, “soul or life” and “body,” “determinative essence and determinate subsistence,” “male principle and female element,” “archæus and body,” the potter and the clay of the potter; or whether again they were “type and individual,” “cause and effect,” “law and nature,” “becoming and being,” or even the “thought and extension” of Descartes, the riddle lay in the contrast of the static and dynamic aspects of things; in the incessant formation of variable and transitory individuals in the eternal ocean of existence25.

“Spiritus intus alit, totamque infusa per artus

Mens agitat molem, et magno se corpore miscet.”

For early thinkers, untrained in the methods and unaware of the limits of thought, even for the great and free thinkers of Greece, a captivating analogy was irresistible26; while inventing schemes of thought they believed themselves to be describing the processes of nature. Moreover it has been the temptation of philosophers of all times, and even of Harvey himself than whom none had put better the conditions of scientific method, to suppose that by means of abstraction kinds may be apprehended; that thus they may get nearer to the inmost core of things; that by purging away the characters of individuals they may detect the essence and cause of individuation (σπερματικὸς λόγος): not perceiving indeed that the content of notions is, as Abélard had pointed out plainly, in inverse proportion to their universality. Like Sidney’s hooded dove, the blinder they were the higher they strove27. For example: from a lump of silver a medal is struck; from many lumps of silver many medals are struck, each different from the other: let us eliminate as accidents the notions of silver, of the blow of a hammer, even of particular features of the devices, and we shall reach the idea of an agent with a type or seal, or of such an agent with many seals, or ideas, who may thus individualise indifferent matter; or, to penetrate deeper into abstraction, who may transfer forms of his own activity to motionless stuff. It is my part to-day to show that before motionless stuff – before the problem of the “primum” mobile” – even Harvey himself stood helpless; helpless yet fascinated by the indulgence of invention when, in the De motu cordis, or the De generatione, he permitted himself to carry contemplation beyond the sphere of his admirable experiments. “Natural, vital and animal spirits” indeed he would have none of; saying well that he should want as many spirits as functions, and that to introduce such agents as artificers of tissues is to go beyond experience: yet in his need of a motor for his machine he was not able to divest himself of the language nor even of the philosophy of his day; he referred the cause of the motion of the blood, and therefore of the heart, to innate heat28. In his day he could not but regard rest and motion as different things; and motion as a super-added quality. In denying the older opinion29 that the heart is the source of motion, of perfection30 and of heat, he put the difficulty but one stage back; and, when in the treatise on Generation he propounded his transcendental notion of the impregnation of the female by the conception of a “general immaterial idea,” we find in him realism still very much alive indeed. Had Harvey been content with innate heat he would have done well enough; but the innate heat of the blood, as he explains it, is not fire nor derived from fire; nor is the blood occupied by a spirit, but is a spirit: it is also “celestial in nature, the soul, that which answers to the essence of the stars … is something analogous to heaven, the instrument of heaven.”

In denying that a spirit descends and stows itself in the body, as “an extraneous inmate,” Harvey advances beyond Cremoninus, who then taught in the chair of Averroistic philosophy in Padua; for, says Harvey, I cannot discover this spirit with my senses, nor any seat of it. In another passage indeed Harvey warns us “not to derive from the stars what is in truth produced at home”; in yet another he tells us that philosophers produce principles as indifferent poets thrust gods upon the stage, to unravel plots and to bring about catastrophes: yet he concludes that “the spirit in the blood acting superiorly to the powers of the elements, … the soul in this spirit and blood, is identical with the essence of the stars.”

Thus the riddle which oppressed these great thinkers, from the Ionians to Lavoisier, was in part the nature of the “impetum faciens31” – of the Bildungstrieb. What makes the ball to roll? Does heart move blood or blood move heart; and in either case what builds the organ and what bestows and perpetuates the motion? Albert of Cologne, and at times even Aristotle, as we have seen, were apt to leave moving things for abstract motion, and to regard formulas as agents. Telesius again, the first of the brilliant band of natural philosophers in Italy of the xvith and xviith centuries, was still seeking this principle of nature in the “form” of the peripatetics. Gilbert regarded his magnetic force as “of the nature of soul, surpassing the soul of man.” Galileo, although willing to conceive circular motion as perpetual32, and even self-existent, was unable thus to conceive rectilineal motion.

Harvey, then, and other naturalists of the time, including Cæsalpinus and after a fashion even Descartes, followed the medieval world and Aristotle in deriving the source of motion directly from the spheres. Harvey says with Dante, “Questi nei cuor mortali è permotore.” The attraction exercised by external supreme mind (not associated with matter) and its thoughts bring the material cosmos and its parts into regular movements. The so-called Αἰθήρ, or fifth element, “στοιχεῖον ἕτερον τῶν τεσσάρων, ἀκήρατόν τε καὶ θεῖον” (De Cælo, cap. 2 and vid. Zeller II. ii. 437), under the name of the Quintessence, played a large part in the speculations of Lulli, Paracelsus and other chemical mystics. Till Copernicus transfigured the cosmos, and Galileo and Newton carried terrestrial physics into the celestial world, the heavenly bodies were regarded as animated beings, themselves set in motion by spheres, and, by propagation of their intense activity from sphere to sphere, animating all sublunary matter, wheels within wheels, even to its innermost particles. Aristotle’s view (Metaph. xi.) was as follows: – The stars and planets are in their nature eternal essences; that which moves them must itself be eternal, and prior and external to that which it causes to be moved; likewise that which is prior to essence must itself be essence; and so on for a hierarchy of eternal essences: thus Heaven if not God is a divine embodiment (Θεῖον σῶμα); and this πρῶτον τῶν σωμάτων he regarded as the essence of heaven and stars, and the cause of animal heat in living beings. Thus the transition from Aristotle to the later conception of the celestial bodies as themselves animated beings was easy; indeed the attribution of intelligence to the spheres goes back at any rate to Plato (Timæus), if not to Pythagoras; and was the foundation of astrology. In Harvey’s time there was still in Rome a basilica of the Seven Angels (the planetary essences). Much of this doctrine Harvey probably got from Cicero (Acad. i. ii. 39 and De Fin. iv. 5-12; vid. Krische), who speaks of “ardor cœli” as the whole astral sphere. If I am not mistaken Harvey somewhere advises Aubrey to study Cicero.

Matthew Arnold thus regrets the old illusion: —

And you, ye stars!* * * *You too once lived —You too moved joyfullyAmong august companionsIn an older world, peopled by Gods,In a mightier order,The radiant, rejoicing, intelligent Sons of Heaven!But now you kindleYour lonely, cold shining lights,Unwilling lingerersIn the heavenly wilderness,For a younger, ignoble world.And renew by necessity,Night after night your courses,   *     *     *     *     *     *     *Above a race you know not,Uncaring and undelighted33.

Of the origin of energy we have not solved the riddle, we have given it up; but instead of coming from without we know that it comes from within. As Mr Benn puts it, we have extended the atomistic method from “matter” to motion. Harvey’s contemporary, Francis Bacon, sagaciously guessed that heat is an expansive motion of particles; but he regarded heat and cold as two contrary principles. Almost in the same generation the brilliant John Mayow perceived a substance in the air “allied to saltpetre,” which passed in and out of the blood by the way of the lungs or placenta. “Innate heat” then gave way to phlogiston; but it was not till the discovery of oxygen and of the conservation of energy that we attained a theory of energy, and finally got rid of “matter and form,” and of all the thicket of metaphysics, relating thereto; through which in the day of Harvey no mind, however mighty, could have made its way.

In the history of medieval thought we must always bear in mind that in neither of its two periods were theology, logic, metaphysics, psychology, or even physics, fully differentiated; and before the Arabian literature they were not differentiated at all34. Logic, which for us is but a drill, and, like all drills, a little out of fashion, was for the Middle Ages a means of discovery, nay, the very source of truth; thus every man carried his own busy laboratory within him. The heirs of Porphyry and Boetius had no other method in their possession. The dialectically irresistible was the true (κατάληψις); thus was man to succeed “irrefutabile aperire secretum.” To begin to think before beginning to learn is a hollow business, yet then logic furnished the theorems which experience might illustrate at its leisure; and nature was contemplated under philosophy. The differentiation of psychology began with the translation of the De anima35, and the recognition of the relation of the percipient; hence, in the second period, Roger Bacon denounced the pretensions of logic, and John Duns, that brilliant backslider, forced them to an absurdity. Again, on the translation of the Metaphysics, theology parted into the studies of the doctrines of God and the soul, which belong to theology proper, and of being, in modes, kinds and universals, which belong to metaphysics. Medicine again was a confusion of spheres, as was theology; the care of the soul and the care of the body were the ends of knowledge, and their means contained all knowledge. Thus when we hear that Alcuin ordered the formal teaching of medicine, it was under the name of “Physica”; and not until the Physics of Aristotle came to light did the various branches of natural history become in their turn not only definite studies but also self-sufficient, aside from the art of healing. To this day the healer keeps the name of “physician”; and the subject at Cambridge the name of Physic. It is well to be reminded that although the soldiers of truth must be separated into several regiments, nevertheless for its edification the healing art must draw, directly or indirectly, on all natural science. Robert of Lincoln, Albert of Cologne, and all the Masters of that time studied medicine – that is τὰ φυσικά – as a solid part of knowledge, which in their apprehension was not only a whole but also a manageable whole. Even Francis Bacon did not realise fully the littleness of man in the presence of nature; he hoped that for his harvest man would on a right method – by, let us say, a reformed astrology and a reformed alchemyquickly surprise the secret of her processes: thus Bacon was the last of the Summists. With the differentiation of the several spheres of knowledge, and the perception of the vastness and variety of each, man has ceased to hold not the unity but the simplicity of nature; and he has given up summaries: the theologian rules no longer in metaphysics and psychology; the physician is no longer the only naturalist.

Systems succeed each other but give each other the hand; it takes many a generation to kill a strong theory outright: realism, shaken by Roscellinus and Abélard, and scotched by Hales and Ockham, survived to mislead Harvey; and still it stretches its withered hand over us in the nursery, in the school, and in the great arguments of life36. Malebranche warned us against our deceptive terminology. “Ils prétendent expliquer, (he says), la nature par leurs idées générales et abstraites, comme si la nature était abstraite.” The methods of the English grammar schools are even now medieval in so far as their teaching begins, as it mostly does still, with abstract propositions.

Mysticism gathered over Germany; in Paris to this day nature is constrained in the artifices of logic and rhetoric; and to this day platonism, chiefly by the influence of the Florentine humanists and perhaps of the Cambridge school of Henry More, has moulded both thought and language in England. John Hunter conceived a “materia vitæ diffusa”; and but yesterday Huxley had to say of Owen’s theory of “spermatic force” that an artillerist might as well attribute the propulsion of a bullet to “trigger force.” We profess Aristotle, and we talk Plato. Even by men of science it is daily forgotten that the only being is the particular. After the Faith then, realism – the belief in principles and kinds having external existence, and in formative essences to be reached by abstract thinking – stood another adversary against natural knowledge.

But, stronger even than realism, was a third adversity – the pride of the human mind. Socrates, although, for ethics and politics, he initiated the inductive method, was disposed to regard physical speculations as but a rational pastime37, and the political and ethical study of man as the only serious engagement of thought. Aristotle took up natural knowledge as an encyclopedist38; he rarely verified his facts and he made no experimental researches39. The medieval church held that “ex puris naturalibus cognoscere” was a meagre and might be a mischievous amusement; and it sought to confine speculations to final causes, that is to the animation of the world by an intelligent Being, as man animates his own instruments: though, as Roger Bacon declared, final causes must have physical means. Even Locke thought nature to be hopelessly complex, and urged that ethics is the proper study of man. The asceticism derived from the East, disdainful of carnal things, brought the dualism of matter and spirit into monstrous eminence; and, in respect of medicine, in a few generations it turned the cleanest people in the world into the most filthy40. Moreover, are we not bound to admit that, as ultimate analysis was dangerous to the synthesis of the Faith, so for unwieldy and unstable societies in which ethical and political habits had not yet become engrained, to descend from transcendental explanations to explanations by lower categories was fraught with some danger to lofty and imposing standards of custom and conduct? Nature is too base, says St Anselm, for us to argue from it to God; we must argue from God to things. Analysis is a disintegrating function; the departure of the scientific enquirer is rather from below upwards: it is not only his bias but also his deliberate method to decline to use the discipline and the conceptions of higher categories until he is satisfied that those of the lower are inadequate. A certain natural process may not be attributed to those of chemistry until those of physics are proved to be inadequate; to another process biological conceptions and methods are denied until those of physics first, and then of chemistry, have been tried and found wanting; psychological conceptions are denied to another until in their turns the physical, the chemical, and the physiological are exhausted41; and so on: and within each category the same economy prevails. Now this scientific economy, perhaps first formulated, or effectively used, by William Ockham, in the phrase “entia non sunt multiplicanda” – known as “Ockham’s rasor” – is what is called now-a-days “materialism”; and there is no doubt that the method, legitimate, nay, imperative, as it is in natural science, may in custom and conduct engender a personal and collective habit of apprehending in lower categories, and even of contentment in them until strong reason be shown to go higher42. A higher order of ideas is put in a lower order of language; the “ὁδος εἰς τὸ κάτω” of Heraclitus. The danger of this attitude lies in loss of effort, of aspiration, and even of imagination; he must stoop on the weary oar who, knowing no anchorage, is ever stemming the drift. Notwithstanding is there in history any lesson sadder than this, that where ideals have been loftiest sin and failure have most abounded? a lesson from which Carlyle learned that “the ideal has always to grow in the real, and often to seek out its bed and board there in a very sorry way.”

Almost to this day then the mechanical arts, presumably concerned rather with the lower categories, have been regarded as base; and the craft even of the laboratory as unworthy of great souls. Anatomy had to labour against antipathy both ecclesiastical and popular; chemistry and mechanics were gross pursuits, unless endowed with the perilous distinctions of alchemy and sorcery. Unfortunately this charge upon the dignity of man was made heavier rather than lighter by Petrarch, and by the later humanists of the Renascence; even in the 17th century we find in Oxford that Boyle was bantered by his friends as one “given up to base and mechanical pursuits.” As Boyle himself put it in his delightful way – “There are many Learned Men … who are apt to repine when they see any Person capable of succeeding in the Study of solid Philosophy, addicting himself to an Art (Chemistry) they judge so much below a Philosopher, and so unserviceable to him. Nay, there are some that are troubled when they see a Man acquainted with other Learning countenance by his example sooty Empiricks” … “whose Experiments may indeed be useful to Apothecaries, and perhaps to Physicians, but are useless to a Philosopher that aims at curing no Disease but that of Ignorance.”43