With regard to this argument, I think in the first place that it is very pious to say and prudent to affirm that the holy Bible can never speak untruth—whenever its true meaning is understood. But I believe nobody will deny that it is often very abstruse, and may say things which are quite different from what its bare words signify. Hence, in expounding the Bible if one were always to confine oneself to the unadorned grammatical meaning, one might fall into error. Not only contradictions and propositions far from true might thus be made to appear in the Bible, but even grave heresies and follies. Thus, it would be necessary to assign to God feet, hands, and eyes, as well as corporeal and human affections, such as anger, repentance, hatred, and sometimes even the forgetting of things past and ignorance of those to come. These propositions uttered by the Holy Ghost were set down in that manner by the sacred scribes in order to accommodate them to the capacities of the common people, who are rude and un-learned. For the sake of those who deserve to be separated from the herd, it is necessary that wise expositors should produce the true senses of such passages, together with the special reasons for which they were set down in these words… .
This being granted, I think that in discussions of physical problems we ought to begin not from the authority of scriptural passages, but from sense-experiences and necessary demonstrations; for the holy Bible and the phenomena of nature proceed alike from the divine Word… . For that reason it appears that nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words.
Robert Bellarmine, Letter to Paolo Foscarini, 1615
First. I say that it seems to me that Your Reverence and Galileo did prudently to content yourself with speaking hypothetically, and not absolutely, as I have always believed that Copernicus spoke. For to say that, assuming the earth moves and the sun stands still, all the appearances are saved better than with eccentrics and epi-cycles, is to speak well; there is no danger in this, and it is sufficient for mathematicians. But to want to affirm that the sun really is fixed in the center of the heavens and only revolves around itself (i.e., turns upon its axis) without traveling from east to west, and that the earth is situated in the third sphere and revolves with great speed around the sun, is a very dangerous thing, not only by irritating all the philosophers and scholastic theologians, but also by injuring our holy faith and rendering the Holy Scriptures false. For Your Reverence has demonstrated many ways of explaining Holy Scripture, but you have not applied them in particular, and without a doubt you would have found it most difficult if you had attempted to explain all the passages which you yourself have cited.
Second. I say that, as you know, the Council [of Trent] prohibits expounding the Scriptures contrary to the common agreement of the holy Fathers. And if Your Reverence would read not only the Fathers but also the commentaries of modern writers on Genesis, Psalms, Ecclesiastes and Josue, you would find that all agree in explaining literally (ad litteram) that the sun is in the heavens and moves swiftly around the earth, and that the earth is far from the heavens and stands immobile in the center of the universe. Now consider whether in all prudence the Church could encourage giving to Scripture a sense contrary to the holy Fathers and all the Latin and Greek commentators. Nor may it be answered that this is not a matter of faith, for if it is not a matter of faith from the point of view of the subject matter, it is on the part of the ones who have spoken… .
Third. I say that if there were a true demonstration that the sun was in the center of the universe and the earth in the third sphere, and that the sun did not travel around the earth but the earth circled the sun, then it would be necessary to proceed with great caution in explaining the passages of Scripture which seemed contrary, and we would rather have to say that we did not understand them than to say that something was false which has been demonstrated. But I do not believe that there is any such demonstration; none has been shown to me. It is not the same thing to show that the appearances are saved by assuming that the sun really is in the center and the earth in the heavens. I believe that the first demonstration might exist, but I have grave doubts about the second, and in a case of doubt, one may not depart from the Scriptures as explained by the holy Fathers.
What does Galileo think is the difference between knowledge about the natural world and knowledge about the spiritual world? What does Galileo suggest that his opponents should do before dismissing his ideas? In what ways does Cardinal Bellarmine attempt to refute Galileo’s ideas? Why did Galileo’s ideas represent a threat to the Catholic Church?
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Galileo made two contributions to the problem of motion. First, he demonstrated by experiments that if a uniform force was applied to an object, it would move at an accelerated speed rather than a constant speed. Moreover, Galileo discovered the principle of inertia when he argued that a body in motion continues in motion forever unless deflected by an external force. Thus, a state of uniform motion is just as natural as a state of rest. Before Galileo, natural philosophers had tried to explain motion; now their task was to explain changes in motion.
The condemnation of Galileo by the Inquisition, coming at a time of economic decline, seriously undermined further scientific work in Italy, which had been at the forefront of scientific innovation. Leadership in science now passed to the northern countries, especially England, France, and the Dutch Netherlands. By the 1630s and 1640s, no reasonable astronomer could overlook that Galileo’s discoveries, combined with Kepler’s mathematical laws, had made nonsense of the Ptolemaic-Aristotelian world system and clearly established the reasonableness of the Copernican model. Nevertheless, the problem of explaining motion in the universe and tying together the ideas of Copernicus, Galileo, and Kepler had not yet been solved. This would be the work of an Englishman who has long been considered the greatest genius of the Scientific Revolution.
Newton
Born in the English village of Woolsthorpe in 1642, Isaac Newton was an unremarkable young man until he attended Cambridge University. His first great burst of creative energy came in 1666, when the fear of plague closed Cambridge and forced him to return to Woolsthorpe for eighteen months. There Newton discovered his creative talents: “In those days I was in the prime of my life for invention and minded mathematics and philosophy more than at any time since.”9 During this period, he invented the calculus, a mathematical means of calculating rates of change; began his investigations into the composition of light; and inaugurated his work on the law of universal gravitation. Two years after his return to Cambridge, in 1669, he accepted a chair in mathematics at the university. During a second intense period of creativity from 1684 to 1686, he wrote his famous Principia (prin-SIP-eeuh). After a nervous breakdown in 1693, he sought and received an administrative post as warden of the royal mint and was advanced to master of the mint by 1699, a post he held until his death in 1727. Made president of the Royal Society (see “The Scientific Societies” later in this chapter) in 1703 and knighted in 1705 for his great achievements, Sir Isaac Newton is to this day the only English scientist to be buried in Westminster Abbey.
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Newton’s Rules of Reasoning
In 1687, Isaac Newton published his masterpiece, the Mathematical Principles of Natural Philosophy, or Principia. In this work, Newton demonstrated the mathematical proofs for his universal law of gravitation and completed the new cosmology begun by Copernicus, Kepler, and Galileo. He also described the rules of reasoning by which he arrived at his universal law.
Isaac Newton, Rules of Reasoning in Philosophy
Rule 1
We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.
To this purpose the philosophers say that Nature does nothing in vain, and more is in vain when less will serve; for Nature is pleased with simplicity, and affects n
ot the pomp of superfluous causes.
Rule 2
Therefore to the same natural effects we must, as far as possible, assign the same causes.
As to respiration in a man and in a beast; the descent of stones in Europe and in America; the light of our culinary fire and of the sun; the reflection of light in the earth and in the planets.
Rule 3
The qualities of bodies, which admit neither intensification nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever.
For since qualities of bodies are only known to us by experiments, we are to hold for universal all such as universally agree with experiments; and such as are not liable to diminution can never be quite taken away.
Rule 4
In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.
This rule we must follow, that the argument of induction may not be evaded by hypotheses.
What are Newton’s rules of reasoning? How important were they to the development of the Scientific Revolution? How would following these rules change a person’s view of the world, of European religious traditions, and of ancient “science”?
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NEWTON AND THE OCCULT Although Newton occupies a very special place in the history of modern science, we need to remember that he, too, remained extremely interested in aspects of the occult world. He left behind hundreds of manuscript pages of his studies of alchemy, and in fact, his alchemical experiments were a major feature of his life until he moved to London in 1696 to become warden of the royal mint. The British economist John Maynard Keynes said of Newton after examining his manuscripts in 1936:
Newton was not the first of the age of reason. He was the last of the magicians… . He looked on the whole universe and all that is in it as a riddle, as a secret which could be read by applying pure thought to certain evidence, certain mystic clues which God had laid about the world to allow a sort of philosopher’s treasure hunt to the esoteric brotherhood. He believed that these clues were to be found partly in the evidence of the heavens and in the constitution of elements, … but also partly in certain papers and traditions handed down by the brethren in an unknown chain back to the original cryptic revelation in Babylonia.10
Isaac Newton. With a single law, that of universal gravitation, Isaac Newton was able to explain all motion in the universe. His great synthesis of the work of his predecessors created a new picture of the universe, one in which the universe was viewed as a great machine operating according to natural laws. Enoch Seeman painted this portrait of Newton one year before his death.
© National Portrait Gallery, London/The Bridgeman Art Library
Although Newton may have considered himself a representative of the Hermetic tradition, he chose, it has been recently argued, for both political and psychological reasons to repress that part of his being, and it is as the “symbol of Western science” that Newton came to be viewed.
UNIVERSAL LAW OF GRAVITATION Newton’s major work, the “hinge point of modern scientific thought,” was his Mathematical Principles of Natural Philosophy, known simply as the Principia, the first word of its Latin title. In this work, the last highly influential book in Europe to be written in Latin, Newton spelled out the mathematical proofs demonstrating his universal law of gravitation. Newton’s work was the culmination of the theories of Copernicus, Kepler, and Galileo. Though each had undermined some part of the Ptolemaic-Aristotelian cosmology, until Newton no one had pieced together a coherent synthesis for a new cosmology.
In the first book of the Principia, Newton defined the basic concepts of mechanics by elaborating the three laws of motion: every object continues in a state of rest or uniform motion in a straight line unless deflected by a force, the rate of change of motion of an object is proportional to the force acting on it, and to every action there is always an equal and opposite reaction. In book 3, Newton applied his theories of mechanics to the problems of astronomy by demonstrating that these three laws of motion govern the planetary bodies as well as terrestrial objects. Integral to his whole argument was the universal law of gravitation, which explained why the planetary bodies did not go off in straight lines but continued in elliptical orbits about the sun. In mathematical terms, Newton explained that every object in the universe was attracted to every other object with a force (gravity) that is directly proportional to the product of their masses and inversely proportional to the square of the distances between them.
The implications of Newton’s universal law of gravitation were enormous, even though another century would pass before they were widely recognized. Newton had demonstrated that one universal law, mathematically proved, could explain all motion in the universe, from the movements of the planets in the celestial world to an apple falling from a tree in the terrestrial world. The secrets of the natural world could be known by human investigations. At the same time, the Newtonian synthesis created a new cosmology in which the world was seen largely in mechanistic terms. The universe was one huge, regulated, and uniform machine that operated according to natural laws in absolute time, space, and motion. Although Newton believed that God was “everywhere present” and acted as the force that moved all bodies on the basis of the laws he had discovered, later generations dropped his spiritual assumptions. Newton’s world-machine, conceived as operating absolutely in time, space, and motion, dominated the Western worldview until the twentieth century, when the Einsteinian revolution, based on the concept of relativity, superseded the Newtonian mechanistic concept.
Newton’s ideas were soon accepted in England, possibly out of national pride and conviction and, as has been argued recently, for political reasons (see “Science and Society” later in this chapter). Natural philosophers on the Continent resisted Newton’s ideas, and it took much of the eighteenth century before they were generally accepted everywhere in Europe. They were also reinforced by developments in other fields, especially medicine.
Advances in Medicine and Chemistry
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FOCUS QUESTION: What did Paracelsus, Vesalius,and Harvey contribute to a scientific view of medicine?
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Although the Scientific Revolution of the sixteenth and seventeenth centuries is associated primarily with the dramatic changes in astronomy and mechanics that precipitated a new perception of the universe, a third field that had been dominated by Greek thought in the Later Middle Ages, that of medicine, also experienced a transformation. Late medieval medicine was dominated not by the teachings of Aristotle but by those of the Greek physician Galen, who had lived in the second century C.E.
Galen’s influence on the medieval medical world was pervasive in anatomy, physiology, and disease. Galen had relied on animal, rather than human, dissection to arrive at a picture of human anatomy that was quite inaccurate in many instances. Even when Europeans began to practice human dissection in the Later Middle Ages, instruction in anatomy still relied on Galen. While a professor read a text of Galen, an assistant dissected a cadaver for illustrative purposes. Physiology, or the functioning of the body, was also dominated by Galenic hypotheses, including the belief that there were two separate blood systems. One controlled muscular activities and contained bright red blood moving upward and downward through the arteries; the other governed the digestive functions and contained dark red blood that ebbed and flowed in the veins.
Treatment of disease was highly influenced by Galen’s doctrine of four bodily humors: blood, considered warm and moist; yellow bile, warm and dry; phlegm, cold and moist; and black bile, cold and dry. Since disease was supposedly the result of an imbalance of humors that could be discerned from the quantity and color of urine, the examination of a
patient’s urine became the chief diagnostic tool. Although purging and bleeding to remedy the imbalance were often harmful to patients, treatment with traditional herbal medicines sometimes proved beneficial.
Paracelsus
Three figures are associated with the changes in medicine in the sixteenth and seventeenth centuries: Paracelsus (par-uh-SELL-suss), Andreas Vesalius (ahn-DRAY-uss vuh-SAY-lee-uss), and William Harvey. Philippus Aureolus von Hohenheim (1493–1541), who renamed himself Paracelsus (“greater than Celsus,” an ancient physician), was born in a small town near Zürich. After leaving home at the age of fourteen, Paracelsus traveled widely and may have been awarded a medical degree from the University of Ferrara. He achieved a moment of glory when he was appointed city physician and professor of medicine at Basel in 1527. But this, like so many other appointments, proved short-lived due to his vanity and quick temper. He could never disguise his contempt for universities and physicians who did not agree with his new ideas:
I am monarcha medicorum, monarch of physicians, and I can prove to you what you cannot prove… . It was not the constellations that made me a physician: God made me… . I need not don a coat of mail or a buckler against you, for you are not learned or experienced enough to refute even one word of mine… . Let me tell you this: every little hair on my neck knows more than you and all your scribes, and my shoebuckles are more learned than your Galen and Avicenna, and my beard has more experience than all your high colleges.11
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