In his cosmology, Descartes began with an Epicurean physics, seeing the world arising out of atoms in motion. Democritos (c. 460–371 BC), in perhaps one of the most prescient pieces of pure intellect, had taught that: ‘Nothing exists except atoms and empty space; everything else is opinions.’ In this atomic theory, all the various kinds of matter differ only in the size, shape and motion of their infinitesimally small atomic constituents. In Descartes’ atomic-deist theories, creation was originally a series of events during which order condensed out of this random atomic behaviour. All matter – whether rocks, trees or monkeys – is merely the combinations of these atoms churning through space, driven by chance. God then had been relegated to the maker of the atoms and the formulator of the broad rules of their motion. By Paley’s time, despite the failure of the theory of vortices, Descartes was popular with deist scientists trying to find new truths about the cosmos in the spirit of the Enlightenment and Age of Reason, but was dismissed by traditional theologians as one of the ‘ancient sceptics who have nothing to set against a designing Deity, but the obscure omnipotency of chance, and the experimental combinations of a chaos of restless atoms’.
In parallel with such philosophical approaches to knowledge itself and new theories about the very state of matter, a fresh style of experimental science flowered in the modern intellectual environment. Deep thought and practical experimentation fed off each other; as one scholar probed into how we know, another tinkered with new devices for observation and discovery. One man in particular helped launch this empirical renaissance. Francis Bacon (1561–1626), in his Advancement of Learning of 1605 and Novum Organum (1620), laid out a template for science to proceed by the accumulation of facts and by the framing of rational, testable hypotheses. This empirical approach was based on the revolutionary notion that truths about the material world should be discovered rationally through experiment, observation and analysis rather than derived from a set of classical philosophical abstractions or presented as a matter of divine revelation. In Novum Organum he wrote: ‘There are and can be only two ways of searching into and discovering truth. The one flies from the senses and particulars to the most general axiom … The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all. This is the true way, but as yet untried.’
Perhaps nothing better exemplifies the new spirit of empiricism that flourished in the second half of the seventeenth century than the experiments of Robert Boyle and his colleague Robert Hooke, two of the most brilliant natural philosophers of their age, who worked together as equals but in origins and personal style were as different as they could be. This was the first generation of natural philosophers who could be considered ‘scientists’ as we understand the word. The Honourable Robert Boyle was the wealthy son of the even more wealthy 1st Earl of Cork; Hooke came from a family of more modest means: his father was a parson who died young. Boyle, educated at Eton, did not attend university. From an early age he had been an avid reader and after schooling at Eton was tutored privately, first in England and then, from the age of fourteen, in Geneva. Back in England at eighteen, he took up chemistry and then settled in Oxford where he built a laboratory and hired the young Hooke to assist him. In pictures painted in his middle age, he looks a magnificent rich dandy, tall, haughty and remote, but in reality he was a frail man, often ill, with a stammer and a mild, kind, generous and refined intellect, to whom many potential honours, including a peerage, were offered. After leaving Oxford for London, in part to take a greater role in the Royal Society, his intellectual interests ranged well beyond the laboratory to philosophy and particularly to the promotion of religion. If anyone of his age had the right to be called a true philosopher of nature, it was Boyle. He never married but lived most of his adult life with his sister Lady Ranelagh. When she died in 1691, he died just a week later.
Robert Hooke, born in 1627, was eight years younger than Boyle. He was born on the Isle of Wight, where his father was vicar of Freshwater. He soon showed an advanced ability in drawing and everything mechanical, but had to make his own way in the world at thirteen, following the death of his father. A small inheritance allowed him to become an apprentice to the painter Sir Peter Lely in London but Hooke soon decided that he had enough skill in that direction without the drudgery of apprenticeship. He entered Westminster School, where he demonstrated an amazing ability to master languages, learnt ‘the six books of Euclid in one week, mastered the organ in twenty lessons, and invented thirty ways of flying’.23 He became an undergraduate at Christ Church College, Oxford, in 1653 where, essentially penniless, he was forced to earn his way as a servant to another student. Nevertheless, he soon made his abilities known to all the scientific luminaries of the age including Christopher Wren and Robert Boyle.
Boyle and Hooke made a superb team, with complementary skills and an equal commitment to the new-fangled Baconian idea that the truth could be found through direct observation and experiment.24 During the twelve years they worked together at Oxford between 1656 and 1668, Boyle and Hooke’s ideas led in every direction. They became particularly famous for investigating the properties of air, which in classical and medieval times was one of the four ‘elements’ (air, earth, fire and water). Using their own version of the air pump that had been invented by Otto von Guernicke, they measured the elasticity of air and found the mathematically precise, inverse relationship between the volume and pressure of a body of air. This is one of the first physical laws to be enunciated and is still known today as Boyle’s law. Boyle’s air pump, built and operated by Hooke, was also intended to show that Aristotle was wrong when he taught that a vacuum was impossible in nature. Attached to their pump (which often broke down) was a glass chamber inside which they could create both high pressure and a (partial) vacuum. They proved that when the air was removed from the chamber, sound could not be transmitted, although light could. A whole mini-revolution was seeded by what might seem to us a very simple piece of apparatus when they also used it to conduct some elementary experiments on the effect of the air on living organisms, putting a bird or mouse into the chamber and evacuating the air. As it was withdrawn, the animal became listless; if the air was restored, it revived. If enough air was withdrawn, the creature died: all commonplace stuff to us, but revolutionary then. They had discovered that there must be some ‘vital essence’ in the air that makes life possible. This, and the eventual discovery of oxygen by Lavoisier, Joseph Priestley and others, launched an investigation into the material (physiological) basis of life itself, a subject with enormous metaphysical implications given that it had always been thought that life was something breathed into creatures by God, not just another property of matter in motion.
Linguist, microscopist, artist, mathematician, mechanical experimenter and inventor, palaeontologist, surveyor – Hooke’s accomplishments were long overshadowed by the fame of the two other geniuses (Boyle and Christopher Wren) with whom he worked. With Boyle he was the master experimenter and inventor – for example of the universal joint, essential to so many modern machines.25 With Wren he was the great engineer. When Wren was made architect for the rebuilding of London after the Great Fire of 1666, Hooke was the chief surveyor; and as Hooke the engineer he gave Wren the parabolic formula for the great dome of St Paul’s