Nevertheless, the expansion of commerce and industry were compelling the development of science. The Platonic and artistic strains in the Renaissance hardly harmonized with the swelling economy; the demand grew for a mental procedure that would deal with facts and quantities as well as with theories and ideas; the Aristotelian empiricism revived, shorn of its Alexandrian and medieval masks. The emphasis of Italian humanism on the glories of ancient literature and art made way for a less ethereal stress on current practical needs. Men had to count and calculate, measure and design, with competitive accuracy and speed; they needed tools of observation and recording; demands arose which were met by the invention of logarithms, analytical geometry, calculus, machines, the microscope, the telescope, statistical methods, navigational guides, and astronomical instruments. Throughout Western Europe lives were henceforth dedicated to meeting these needs.
In 1614 John Napier in Scotland and in 1620 Joost Bürgi in Switzerland independently proposed a system of logarithms (i.e., a logic of numbers) by which products, quotients, and roots could be quickly calculated from the tabulated relation of the given numbers as powers of a fixed number used as a base. Henry Briggs (1616) modified the method for common computation by proposing 10 as a base, and published tables giving the logarithms of all numbers from one to 20,000. Now two numbers could be multiplied by finding, in such tables, the number whose “log” was the sum of the logs of the numbers to be multiplied; and a could be divided by b by finding the number whose log was the log of b subtracted from the log of a. William Oughtred (1622) and Edmund Gunter (1624) constructed slide rules by which the results of logarithmic calculations could be read in a few seconds. These inventions halved the time given to arithmetical work by mathematicians, astronomers, statisticians, navigators, and engineers, and in effect lengthened their lives.9 Kepler, who used the new method in computing planetary motions, addressed an enthusiastic panegyric to the Laird of Merchiston (1620), not knowing that Napier was then three years dead. Napier himself had made a little miscalculation, having figured that the world would come to an end between 1688 and 1700.10
Mathematicians and astronomers were still closely allied, for the reckoning of celestial motions, the charting of the calendar, and the guidance of navigation required complex manipulations of astronomic measurements. As a mathematician, Thomas Harriot established the standard form of modern algebra, introduced the signs for root, “greater than” and “less than,” replaced clumsy capitals with small letters to indicate numbers, and hit upon the beneficent trick of placing all the quantities in an equation on one side and zero on the other. As an astronomer, he discovered the spots on the sun, and his observations of Jupiter’s satellites were made independently of Galileo’s. George Chapman, himself a monster of learning, thought Harriot’s knowledge to be “incomparable and bottomless.”11
Astronomy was still dripping with astrology. “Horary” astrology decided whether the stars favored the enterprise of the hour; “judicial” astrology foretold affairs in general, usually with judicious ambiguity; “natural” astrology disclosed the destiny of an individual from his horoscope—an examination of the position of the stars at the moment of his birth; all these are found in Shakespeare (though not proving his belief), and in our time. The moon, in astrological theory, produced tides, tears, madmen, and thieves (cf. Shakespeare, I Henry IV, I, ii, 15), and each sign of the zodiac controlled the character and fate of specific organs in the human anatomy (Twelfth Night, I, iii, 146–51). John Dee symbolized the time by mingling astrology, magic, mathematics, and geography: he engaged in crystal gazing, wrote a Treatise of the Rosie Crucean Secrets, was charged with practicing sorcery against Queen Mary Tudor (1555), drew up geographical and hydrographical charts for Elizabeth, proposed a northwest passage to China, invented the phrase “the British Empire,” lectured on Euclid before large audiences in Paris, defended the Copernican theory, advocated the adoption of the Gregorian calendar (170 years before England resigned itself to such a papistical contraption), and died at eighty-one; here was a full life! His pupil, Thomas Digges, promoted the acceptance of the Copernican hypothesis in England, and anticipated Bruno’s notion of an infinite universe.12 Thomas and his father, Leonard Digges, used “perspective glasses” which were probably forerunners of the telescope; and William Gascoigne invented (c. 1639) the micrometer, which enabled observers to adjust a telescope with unprecedented accuracy. Jeremiah Horrocks, a poor Lancashire curate who died at twenty-four, ascribed an elliptical orbit to the moon, and predicted—and observed (1639) for the first recorded time—the transit of Venus across the sun. His speculations on the forces moving the planets helped Newton to the theory of universal gravitation.
Meanwhile the study of terrestrial magnetism was also preparing for Newton. In 1544 Georg Hartmann, a German clergyman, and in 1576 Robert Norman, an English compass maker, independently discovered the tendency of the magnetic needle, when freely suspended at its center of gravity, to “dip” from a horizontal position to one at an angle to the earth’s surface. Norman’s book, The Newe Attractive (1581), suggested that the “joynt Respective” to which the needle dipped lay within the earth.13
This fascinating lead was followed by William Gilbert, physician to Elizabeth. After seventeen years of research and experiment—financed by his inherited fortune, and sometimes watched by the Queen—he set forth his results in the first great book of English science, De magnete … et de magno magnete tellure (1600)—On the Magnet … and the Great Magnet the Earth. He laid a pivoted compass needle successively at different points upon a globular lodestone, he marked with lines on the globe the directions in which the needle successively set, he prolonged each line to form a great circle around the stone, and he found that all these circles crossed at two diametrically opposite points on the globe; these were the magnetic poles, which, in the case of the earth, Gilbert mistakenly identified with the geographical poles. He described the earth as an enormous magnet, explained thereby the behavior of the magnetic needle, and showed that any iron bar left for a long time in a north-and-south position would become magnetized. A magnet placed at either pole of the globular lodestone took a position vertical to the globe; placed at any point midway between the poles (such points constituting the magnetic equator), the magnet lay horizontal. Gilbert concluded that the dip of the needle would be greater the nearer it was placed to the geographical poles of the earth; and though this was not quite correct, it was approximately confirmed by Henry Hudson in his exploration of the Arctic in 1608. From his own observations Gilbert drew up directions for calculating latitude from the degree of the magnetic dip. He suggested that “from about a magnetic body the virtue magnetical is poured out on every side”; he ascribed the rotation of the earth to the influence of this magnetic field. Passing on to the study of electricity—wherein little had been done since antiquity—he proved that many other substances besides amber could, when rubbed, generate frictional electricity; and from the Greek for amber he formed the word electric to denote a power to deflect a magnetic needle. He believed that all heavenly bodies are endowed with magnetism; Kepler was to use this idea to explain the motion of the planets. Most of Gilbert’s work was an admirable example of experimental procedure, and its effects on science and industry were immeasurable.
The advance of science appeared more dramatically in the efforts of adventurous or acquisitive spirits to explore the “great magnet” for geographical or commercial purposes. In 1576 Sir Humphrey Gilbert (no kin to William) published a suggestive Discourse … for a New Passage to Catata—i.e., “Cathay,” or China—proposing a northwest sailing through or around Canada. Sir Martin Frobisher, in that year, set out with three small vessels to find such a route. One of his ships foundered, another deserted; he went ahead in the tiny twenty-five-ton Gabriel; he reached Baffin Land, but the Eskimos fought him, and he returned to England for more men and supplies. His later voyages were diverted from geography by a vain hunt for gold. Gilbert took up the quest for a northwest passage, but was drowned in the attempt (1583). Four years later John Davys pushed through the strait now named for him; then he fought the Armada, went off to the South Seas with Thomas Cavendish, discovered the Falkland Islands, and was killed by Japanese pirates near Singapore (1605). Cavendish explored southern South America, accomplished the third circumnavigation of the globe, and died at sea (1592). Henry Hudson navigated the Hudson River (1609), and, in another voyage, reached Hudson Bay; but his crew, maddened with hardships and longing for home, mutinied and set him adrift, with eight others, in a small open boat (1611); they were never heard of again. William Baffin explored the bay and the island that bear his name, ventured as far north as 77° 45’—a latitude not reached again for 236 years—and had the further distinction of first finding longitude by observation of the moon. Richard Hakluyt saw in such ships and hearts of oak an epic of courage and terror surpassing any Iliad, and he gathered their narratives into successive volumes, the best-known of which are those published as The Principal Navigations, Voyages, and Discoveries of the English Nation (1589, 1598–1600); Samuel Purchas expanded the record in Hakluytus Posthumus, or Purchas his Pilgrimes(1625). So, by the greed for gold or trade, and the zest for far-off peril and scenes, geography unwittingly grew.
The best work of this age in physics, chemistry, and biology was done on the Continent; in England, however, Sir Kenelm Digby discovered the necessity of oxygen to plant life, and Robert Fludd, mystic and medico, advocated vaccination 150 years before Jenner. Medical prescriptions continued to rely on their repulsiveness for their effect; the official London pharmacopoeia of 1618 recommended bile, blood, claws, cockscomb, fur, sweat, saliva, scorpions, snakeskin, wood lice, and spider web as medicaments; and bloodletting was a first resort.14 Nevertheless this period boasts of Thomas Parr (“old Parr”), who was presented to Charles I in 1635 as still in good health at the alleged age of 152. Parr did not profess to know his exact age, but his parish authorities dated his birth in 1483; he claimed to have joined the army in 1500, and he recalled in detail the dissolution of the monasteries by Henry VIII (1536). “You have lived longer than other men,” said Charles I. “What have you done more than they?” Parr replied that he had fertilized a wench when he was over a hundred years old and had done public penance for it. He had subsisted almost entirely on potatoes, greens, coarse bread, and buttermilk, with rarely a taste of meat. For a while he became a lion in London parlors and pubs, and he was so handsomely feasted that he died within a year of meeting the King. Sir William Harvey performed a post-mortem on him, found him free of arteriosclerosis, and diagnosed his death as due to change of air and food.15
It was Harvey who provided the scientific climax of the age by explaining the circulation of the blood—”the most momentous event in medical history since Galen’s time.”16 Born at Folkstone in 1578, he studied at Cambridge, then at Padua under Fabrizio d’Acquapendente. Returning, he settled down to medical practice in London, and became personal physician to James I and Charles I. Through patient years he carried on experiments and dissections on animals and cadavers, and particularly studied the flow and the course of blood in wounds. He came to his main theory in 1615,17 but belatedly published it at Frankfurt in 1628 as a modest Exercitatio anatomica de motu cordis et sanguinis in animalibus—the first and greatest classic in English medicine.
The steps to his discovery illustrate the internationalism of science. For over a thousand years the functions of heart and blood had been interpreted as by Galen in the second century A.D. Galen had supposed that blood flowed to the tissues from the liver as well as the heart; that air passed from the lungs to the heart; that the arteries and veins carried twin streams of blood, which were propelled and received by the heart in tides of ebb and flow; and that blood passed from the right to the left side of the heart through pores in the septum between the ventricles. Leonardo da Vinci (c. 1506) questioned the view that air passed from lungs to heart; Vesalius (1543) denied the existence of pores in the septum, and his masterly sketches of arteries and veins revealed their terminals as so minute and neighborly as almost to suggest passage and circulation; Fabrizio showed that valves in the veins made it impossible for venous blood to flow from the heart. The Galenic theory faded away. In 1553 Michael Servetus, and in 1558 Realdo Colombo, discovered the pulmonary circulation of the blood—its passage from the right chamber of the heart through the pulmonary artery to and through the lungs, its purification there by aeration, and its return via the pulmonary vein to the left chamber of the heart. Andrea Cesalpino (c. 1571) tentatively—as we shall see—anticipated the full theory of circulation. Harvey’s work turned the theory into a demonstrated fact.
While Francis Bacon, his patient, was extolling induction, Harvey proceeded to his illuminating conclusion by a striking combination of deduction and induction. Estimating the amount of blood pressed out of the heart by each systole, or contraction, to be one half a fluid ounce, he calculated that in half an hour the heart would pour into the arteries over 500 fluid ounces—a larger quantity than the entire body contained. Where did all this blood come from? It seemed impossible that so great a quantity should be produced, hour after hour, from the digestion of food. Harvey concluded that the blood pumped out of the heart was returned to it, and that there was no other apparent avenue for this but the veins. By simple experiments and observations—as by pressing a finger upon some superficial vein—it was readily shown that venous blood flowed away from the tissues and toward the heart.
When I surveyed my mass of evidence, whether derived from vivisections and my previous reflections on them, or from the ventricles of the heart and the vessels that enter into and issue from them … and frequently and seriously bethought me … what might be the quantity of blood which was transmitted … and not finding it possible that this could be supplied by the juices of the ingested aliment without the veins on the one hand becoming drained, and the arteries on the other getting ruptured through the excessive charge of blood, unless the blood should somehow find its way from the arteries into the veins, and so return to the right side of the heart; when, I say, I surveyed all this evidence, I began to think whether there might not be a motion as it were in a circle… And now I may be allowed to give my view of the circulation of the blood.18
He had long hesitated to publish his conclusions, knowing the conservatism of the medical profession of his time. He predicted that no one over forty years of age would accept his theory.19 “I have heard him say,” reported Aubrey, “that after his book of theCirculation of the Blood came out, he fell mightily in his practice, and ‘twas believed by the vulgar that he was crack-brained.”20 Not until Malpighi in 1660 demonstrated the existence of capillaries conveying blood from the arteries to the veins did the learned world concede the circulation to be a fact. The new view illuminated almost every field of physiology, and affected the old problem of the interrelation between body and mind. Said Harvey:
Every affection of the mind that is attended with either pain or pleasure, hope or fear, is the cause of an agitation whose influence extends to the heart … In almost every affection [emotion] … the countenance changes, and the blood appears to course hither and thither. In anger the eyes are fiery and the pupils contracted; in modesty the cheeks are suffused with blushes … in lust how quickly is the member distended with blood!21
Harvey continued to serve Charles I almost to the latter’s bitter end. He accompanied Charles when revolution drove the King from London, was with him at the battle of Edgehill, and narrowly escaped death.22 Meanwhile the rebels sacked his London house and destroyed his manuscripts and anatomical collections. Perhaps he had made a variety of enemies by his sharp temper and views. He rated man as “but a great mischievous baboon,” says Aubrey, and thought that “we Europeans knew not how to order or govern our Woemen,” and that “the Turks were the only people who used them wisely.”23 Still vigorous at seventy-three, he published a treatise on embryology, Exercitationes de generatione animalium (1651). Rejecting the prevalent belief in the spontaneous generation of minute organisms out of decaying flesh, Harvey held that “all animals, even those that produce their young alive, including man himself, are evolved out of an egg”; and he coined the phrase Omne animal ex ovo—”Every animal comes from an agg.” He died six years later of paralysis, bequeathing most of his fortune of twenty thousand pounds to the Royal College of Physicians, and ten pounds to Thomas Hobbes “as a token of his love.”