Aristotle to Copernicus

Introduction: Medieval and early modern European scholars viewed questions about the world and science as primarily a religious and/or theological issue. Religious teaching permeated all thought and activity. An example is the political theory of Divine Right. Religious teachings dominated all aspects of life, from marriage and divorce even to eating habits. However, as Europeans, particularly the upper classes, became more economically secure and better educated, their view of the world became decidedly more secular if not completely scientific. This change was primarily the result of the Scientific Revolution, a time when modern science based on the union of experimental observation and sophisticated mathematics emerged.

Western civilization is the only civilization to develop modern science. One historian has gone so far as to state that the Scientific Revolution was "the real origin of the modern world and the modern mentality." Unquestionably, its scientific achievements more than any other element have set Western society apart.

The Medieval Legacy: Up through the early sixteenth century, the ideas of Aristotle still dominated Western scientific thinking. Aristotle had been lost to the West, but with the capture of Toledo, Spain from the Muslims in 1095, knowledge of Aristotle was re-established. The great thinkers of the day found Aristotle’s ideas in harmony with the teachings of the Bible, and therefore considered them infallible. A prime example is Aristotle’s distinction between the substance of a thing and its appearance, its accidents. This distinction led the Fourth Lateran Council to adopt a new technical term: Transubstantiation. Supreme irony that it may appear, the "Arabized" Aristotle became the presiding genius of the created (Western Christian) world.

Medieval education was "scholastic," that is, academic, and all important writers of the period were "scholastics." Hence, scientific thinking of the period was called Scholasticism, the combination of the Bible and Aristotle. Education was aimed more at refining existing thought than breaking new ground. Experimentation was discouraged. Medieval Universities were set up in which students followed a prescribed course of study upon completion of which they were awarded degrees which certified to their proficiency. Lessons consisted of lectures and textbooks which frequently had to be shared by several students since they were expensive.

Aristotle had prescribed that the earth sat motionless at the center of the universe, and was surrounded by eight transparent crystal spheres which moved around it. In these spheres, the moon, sun, and five known planets were embedded. The stars were also embedded in these spheres, and considered to be fixed in space. These spheres were hierarchical, and became purer as one traveled further out the cosmos. Since in reality the stars move, and their position in the sky changed over time, medieval thinkers, rather than question Aristotle’s thinking, added two more spheres to accommodate the change in position. Beyond the tenth hemisphere, according to medieval thinkers, was heaven where the throne of God and the souls of all the saved existed. The ten spheres were kept in perfect motion by angels.

Aristotle also drew a sharp distinction between the celestial spheres and the earth, which he called the "sublunar" world. The spheres of the heavens constituted a perfect, incorruptible "quintessence," or fifth essence. The sublunar world was made up of four imperfect and changeable elements: the "light" elements, air and fire, which naturally moved upward, and the "heavy" elements, earth and water, which naturally tended downward. Aristotle also said that these elements often interacted with each other, and could be influenced by an outside force, such as the manipulations of a human being; thus the "natural" characteristics of the four elements did not always apply. Aristotle also taught that the natural status of an object was at rest; a "noble" state than motion. Therefore a uniform force could move an object at a constant speed, but once the force was removed, the object would immediately return to a state of rest, and remain motionless. To Aristotle, all the terrestrial bodies naturally moved toward the earth, unless they were propelled in another direction by contact with another object. When the contact with the other object ceased, the object stopped moving or fell back to earth.

Aristotle’s teachings about astronomy and physics were accepted, with minor revisions, for almost two thousand years. Since his conclusions were based on visual inspection, they were a common sense, (and therefore understandable) explanation for that which the eye saw. Also, medieval philosophers found Aristotle’s teachings in tandem with those of scripture. It put human beings, God’s greatest creation, at the center of the universe. It also established a physical location for God and heaven. Human beings were at the center of a "great chain of being" that reached from the throne of God to the lowliest form of visible life on earth. Explanations of scientific questions were always considered in light of God’s "perfect creation."

The Medieval church neatly divided the entire universe into two camps: good and evil. The earth was heavy, weighed down with corruption and sin as well as its own weight. Angels, who were essentially weightless beings, existed in heaven, outside the farthest sphere. The goal of humankind was to attain the lightness of heaven by freeing oneself from the weight of sin.

It is interesting how one sees only that which he wants to see. The Medieval idea of God’s creation being "perfect" actually contradicts scripture itself. Genesis 1:31 states, "And God saw everything that He had made, and behold it was very good." Very good is a long way from perfect. An 88 is very good; 100 is perfect.

Actually, things haven’t changed much. For many years, scientists could not figure out how Neanderthals could have survived in a hostile world, as the sole remains they had found showed a creature which had enlarged gnarly joints and stooped over. How could such a person have hunted game, let alone avoid becoming the hunted himself. Rather than consider that their assumptions about Neanderthals was wrong, they devised all sorts of weird hypotheses, including the idea that they were actually scavengers, not hunters; and that they survived because wild animals did not care for the taste of human flesh. In the 1970’s other skeletal remains were found which showed Neanderthals were not much different from modern man. The skeleton they had studied earlier was of an older (age 35-40) adult who suffered from rheumatoid arthritis; hence the enlarged joints. Modern science: if it doesn’t fit, make it fit.

Aristotle’s ideas were supplemented, and partially explained in the second century A.D. by a Greek astronomer, Claudius Ptolemy who published a massive work known as the Almagest, (Arabic for "greatest.) Ptolemy described the Quadrant, and other instruments which the Arabs had invented, and tried to measure the orbits of the sun, moon, and planets. He accepted Aristotle’s position that the earth was surrounded by the spheres, and that the most distant sphere contained the furthest stars, which Ptolemy believed to be fixed points of light. He also believed that the planets traveled in spherical orbits, but since observation did not bear this out, he determined that there were minor variations in the orbits, which he called "precession." This precession made it possible to explain, and predict, the movements of heavenly bodies even though that movement did not appear to be a perfect sphere.

The thinking of Aristotle and Ptolemy was adopted by Dante Alighieri in the Divine Comedy. In the Inferno, Dante and the Roman Poet Virgil, travel to the core of the earth where they find hell. They then climb out the other side, in the Southern Hemisphere, where they find Purgatory, (Purgatorio) and finally ascend to the tenth sphere where they find heaven. Paradiso)

The Work of Copernicus: There were some early challenges to Aristotle’s thinking, primarily his ideas on a perpetual state of motionlessness. Archimedes of Syracuse (c. 287 – 212 B.C.E.) had challenged Aristotle’s notion that rest was the natural state for an object, and that an "active mover" was needed to generate motion. Nicholas of Cosa, (1401-1464) had speculated that the earth might actually be in motion. Leonardo da Vinci also speculated that the earth might move around the sun. None of these theories went beyond speculation, however; no attempt was made to explain or prove its validity mathematically.

The first major departure from Aristotle’s thinking was the work of Nicolaus Copernicus (1473 – 1543). Copernicus was born in Poland, and as a young man had studied church law and astronomy at a number of European universities. At the time of his study, the teachings of Aristotle as modified by Ptolemy were still considered unimpeachable. The pseudo-science of astronomy, the belief that the position of the stars influenced the future, was prevalent.

Copernicus considered Ptolemy’s calculations to be cumbersome, if not inaccurate. To him, the idea of a heliocentric universe was more sensible. This idea was not new to him; a number of ancient Greek scholars (Aristotle being the notable exception) had also hypothesized that the earth and planets revolved around the sun. This idea had gained new interest in Renaissance Italy, although it was primarily a matter of intellectual speculation. Copernicus worked on his ideas from 1506 to 1530, but never questioned Aristotle’s belief in crystal spheres or that a circular motion was almost perfect and therefore divine. In fact, his own conception of the solar system, although heliocentric, shows the planets revolving around the sun in perfect circular orbits, like the grooves on a CD. He accepted Aristotle’s idea that the spherical universe was finite, and that it was perhaps limited by the stars which he considered fixed. He believed that the movement of the stars was caused by the earth’s rotation. He made some serious errors in his calculations, and did not appear interested in carrying on his observations. He also could not explain why there was no constant wind from the east, as he assumed (incorrectly) that the earth moved to the east in its revolutions around the sun. He did however, conclude that the earth rotates on its axis once a day and revolves around the sun every 365 days.

In the middle of all this sits the Sun enthroned. How could we place this luminary in any better position in this most beautiful temple from which to illuminate the whole at once?

Copernicus also suggested that his astronomical theories could be proven mathematically. He published his findings in his major work, On the Revolutions of the Heavenly Bodies. However, he did not wish to invite ridicule from the established scientific community, and therefore did not publish it until 1543, when he was on his deathbed. Ironically, Copernicus dedicated his work to the Pope; he seemingly was unaware of the intense theological debate his work would generate.

The repercussions of Copernicus’ theories were as vociferous as was the shock they created. His theories suggested that the universe was considerably larger than had once been thought. If he were correct, the universe would be infinitesimally gigantic. Also, by making the earth just another planet in the solar system; a mere player rather than the star attraction, he completely nullified Aristotle’s argument that the earth was different from the other heavenly bodies. His ideas left no place for perfection, or for heaven and the throne of God.

Oddly, Protestants attacked Copernicus’ ideas more than Catholics. Even before his works were published, Martin Luther had caught wind of them and spoke of him as "the new astrologer who wants to prove that the earth moves and goes round….This fool wants to turn the whole art of astronomy upside down." Luther also noted that "as the scripture tells us, so did Joshua bid the sun stand still, and not the earth." Calvin cited the words of Psalm 93 to dispute Copernicus: "The world also is established that it cannot be moved." Calvin then wrote, "Who will venture to place the authority of Copernicus above that of the Holy Spirit. The Catholic Church had never completely adopted a literal interpretation of scripture as has Luther and Calvin and thus did not react as violently; however in 1616, the Church declared Copernicus’ theories false. Even Jewish scholars condemned his work. It was inconceivable that mere humans were themselves hurtling through space at breakneck speed, while peering into the sky.

Observation of the sky had almost as much affect (if not more) in changing thoughts about the nature of the universe as had Copernicus’ writings. In 1562, a "new star" appeared, and shone brightly for two years. It was in reality a distant exploding star. Also, in 1577, a hitherto unknown comet appeared which cut a straight path across the presumably impenetrable spheres of the heavens. Nature itself seemed to be moving to prove Aristotle and Ptolemy wrong.