Galileo is frequently pictured as the inaugurator of true science, because, unlike his medieval predecessors, he stopped thinking in accordance with the nebulous metaphysics of Plato and Aristotle and actually started examining nature through experiments. He is talked of as if he had the mentality of a twenty first century research student at MIT or Imperial College. Needless to say – or it would be needless to say were it not such a widespread perception – this is a complete misreading. He was a civilized gentleman living in the period of the late sixteenth century Italian Renaissance. What that meant was, as with nearly every other cultured and intelligent person living in that time and place, he was a devoted disciple of Marsilio Ficino’s neo-Platonism. Plato had taught that the material and visible things we see around us in this world are only imperfect and corruptible copies of immaterial and invisible entities that Plato called forms. These forms are themselves only different facets of an ultimate higher unity that he called The One.
The material things of this world are only indirect expressions of the perfection they reflect. Indeed, we would not even know of the existence of The One were it not that there is one way in which it does it express itself directly in our imperfect material universe. It is through beauty and mathematics, which are indissolubly linked with each other. Geometry is of supreme importance, for it is through geometry that mathematical concepts are embedded in material things. Above the doorway to Plato’s Academy had supposedly been written ‘ Let none enter here who knows not geometry’. Thjs doctrine was Christianized by Ficino, for whom Plato’s mathematical beauty was at the heart of truth. Beauty is mathematical and mathematics is eternally and irrefutably true, which is what makes it beautiful. Crucial to Ficino’s vision of Christianity was the biblical figure of Wisdom, the intermediary between the divine source of all this mathematical beauty and the material beauties of the world: ‘when he prepared the heavens I was present, when with law and compass he composed the depths…when he drew a circle on the face of the deep’. This wisdom was mysteriously both God and not God. It was the Logos of St John’s Gospel. Logos was a Greek philosophical term that had come down from Heraclitus and it meant something like ‘the rationality of the universe’. In the beginning, the Logos, said St John, was both with God and was God. The rationality of the universe, you could translate it, was both God and not God. This Logos was for Ficino essentially mathematical. Mathematics was in one sense of course not God, but in another it was indistinguishable from the divine, as thoughts cannot be separated from the mind that thinks them, and it was the medium through which God had created the world. Ficino’s doctrine is the key to the mind of Galileo. ‘Nature is a book’ Galileo famously wrote ‘and its language is mathematics’.
In Aristotelian physics the default position of any entity was to be static. It would only move if you gave it a push. You give something a push and when you stop pushing it, it stops moving. But what about a ball thrown up into the air? You lose immediate physical contact with it but even though you have stopped pushing it the ball keeps on rising. Aristotle explains this by saying that it may have lost contact with your push but it has not lost contact with the air you also pushed. You push the air with your hand which pushes the ball until the energy you gave to the air runs out and then the ball starts to fall back to the ground. The essence of Galileo’s discovery of inertia is that things are not naturally static but, once they start to move, continually moving. And not only that. Once they start to move they will keep on moving for ever unless they are impeded, which they always are. Whereas in Aristotle’s physics it was the air which conferred momentum on the ball, in Galileo’s it is the air which halts the ball. Whereas in Descartes’ corpuscular physics, which claimed to be based on Galileo’s discovery of momentum but actually misunderstood it completely, corpuscles move because one particle pushes another, in Galileo’s they move of themselves mathematically. Curiously enough, this supposed great father of experiment was not particularly interested in experiments. In the Discorsi, Simplicio constantly misunderstands the points that Salviati , who is Galileo himself, makes:
‘Simplicio: So you have not made a hundred tests, or even one? And you so freely declare it to be certain.
Salviati: Without experiment, I am sure the effect will happen as I tell you, because it must happen that way; and I might add that you yourself know it cannot happen otherwise, no matter how you pretend not to know it. ‘
When we look closely at Galileo’s experiments we find that they were not demonstrating the law of inertia at all, but the very opposite. They didn’t show the ball continuing to move but, on the contrary, the air stopping the ball. But what they did show was that the air stopped the ball in a mathematically regular sequence of time related to distance. They showed that as time went on the ability of the air to halt the ball increased. What mattered was what experiment couldn’t show but the insight that could be deduced from it. It was the for ever that excited him. If it was the air that was stopping the ball, the implication was that if you could take away the air, although you never could, the ball would never stop. Again and again in the Dialogo and still more in the Discorsi, it is not experiment but geometry to which he returns.
What was important for Galileo was not that he had dismissed the nebulous ideas of Plato but precisely the opposite. What he was showing was that Plato’s eternally true and invisibly immaterial mathematics underlay the material realities of the world, just as Plato had said, and it was these immaterial forces that made the world work. Engineers hurling cannon balls at fortresses, using calculations based on Galileo’s principle that a projectile will keep on moving unless it is stopped by air, began to knock down fortress walls with spectacular success. Cannon balls dropped from the leaning tower of Pisa – actually it is probably a myth that Galileo ever did that – do not fall as they do because they are heavy but because distance of fall is proportional to the square of the elapsed time.
Galileo was a full-blown Platonist, even to the point of believing in Plato’s doctrine of anamnesis, the idea that once, before this present time, we had lived a divine life from which we have been expelled but which in glimpses and flashes we remember, particularly when reminded by beauty and mathematicss:
‘And I, I say to you that if one does not know the truth by himself, it is impossible for anyone else to give him that knowledge. It is indeed possible to teach those things that are neither true nor false; but the true, by which I mean necessary things, that is, those for which it is impossible to be otherwise, every average mind either knows by itself, or it is impossible for it ever to learn them.’
And again: ‘The solution of the question under discussion implies the knowledge of certain truths that are just as well known to you as to me. But, as you do not remember them, you do not see that solution. In this way, without teaching you, because you know them already, but only by recalling them to you, I shall make you solve the problem yourself.’
It is an irony of Galileo’s trial that nothing could have been more Catholic than Galileo’s physics. Thjs is because Catholicism is essentially a sacramental religion. It does not think that God exists outside nature but deeply within it. ‘God dwells within the universe and that innermostly’ wrote Aquinas. Its core belief is that God dwells in the depths not only of the seven sacraments but in all natural forms, which is why, according to Ficino, they are so beautiful. Thjs indwelling of God in the world reached its climax in the incarnation of God in a human body. Through his Passion and Resurrection Christ takes not only all of mankind but the whole of creation into its future transcendental condition. It’s true that mankind sinned in the Fall. But the Fall was also, the liturgy says, a felix culpa. God turns even evil into good, for but for the Fall there would have been no Resurrection and Redemption. What Galileo was showing was that God is indeed indwelling and working in the world, and s(h)e does it through mathematics. Until his trial science had been a largely Catholic enterprise, but now fear of the fires of the Inquisition killed science in the Catholic south and drove it northwards, where it became almost exclusively Protestant.
Now meanings were attributed to Galileo’s discoveries within a completely different theological context. The divine Wisdom that had been so much at the heart of Catholic science was now seen to be an idolatrous blasphemy. Whereas Catholic theology had been essentially sacramental, Protestant was essentially sacrificial. In Catholic theology nature had been fundamentally good, although spoilt by original sin. In Luther’s theology nature, and especially human nature, was irrevocably evil. Only a perfect sacrifice, that of God’s own son, could appease God’s anger and return human beings to God’s grace. Whereas before, mankind had been saved by the Church, now it is the individual’s act of faith that saves. Whereas before the trial the Wisdom that dwelt in the depths of nature had been seen as inseparable from God, and nature was therefore thought to be alive because it was divinely ensouled –the Dame Nature of medieval myth – now nature and God were sharply separated. Now, the nature that was the object of Protestant science was a dead and soulless mechanism. Beauty that had been so important a part of reality for Ficino is not an objective part of nature at all, and certainly not part of the mandate of science, but the subjective province of poets. God is entirely outside nature and, in Paley’s later classic statement of the Protestant theology of creation, does not dwell within it as the soul dwells in the body, but constructs it from the outside as a watchmaker constructs a watch.
I think this history is of the most extraordinary importance in understanding contemporary atheism. Gradually those puzzling motions of a purely mechanical nature, which God had been evoked to explain, became explained much better by science itself. The planets were not kept rolling in their courses by God’s almighty hand but by Newton’s laws of motion. Species had not been directly created by God but had evolved naturally in accordance with natural selection. Now even the beginning of the universe can be explained naturally by quantum physics. There was less and less of a role for God to play until, driven out of one gap after another, he finally vanished altogether. My complaint about atheists is not so much about what they say, so much of which is so admirable, but the conceptual framework within which they say it. Their thinking is still deeply embedded within this Protestant history of science. They are, in fact, Protestant atheists minus the Protestantism. They get atheist answers because they never ask a Catholic question. It never occurs to them to consider a God who is not outside the universe but, we might speculate, deeply within it, indeed IS the universe in its deepest place. The Catholic question is not ‘how do we explain why nature is so mechanically complex?’ as Paley’s was, but ‘how do we explain its wonder?’