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Courses Taught INTELLECTUAL HERITAGE (at Temple
University) Delphi- A Focal Point for IH 51 Texts Subject Study Aids: Aeschylus' Libation Bearers Study Guide Sophocles' Oedipus and the Sphinx Lecture Dr. J's Illustrated Pericles' Funeral Oration Dr. J's Illustrated Pericles and America Dr. J's Illustrated Pericles and Philadelphia Dr. J's Illustrated Aeschylus' Oresteia Dr. J's Curse of the House of Atreus Outline Dr. J's Background Lecture on Greek Philosophy Dr. J's Apology Study Questions Dr. J's Illustrated Plato's Apology Socrates and the Apology Lecture Epic Qualities of the Sundiata Lecture RELIGIOUS FOUNDATIONS OF CLASSICAL GREECE Courses Proposed Religious Foundations of Greek Culture The Intersection of Myth and History The Ancient Greek Cultural Nexus- Art, Archaeology, Literature and Topography |
From 1996-2001 I taught in the Intellectual Heritage Program at Temple University in Philadelphia, Pennsylvania. This page is part of my teaching materials for Intellectual Heritage 51, a course covering literature and ideas from Sappho through Shakespeare... Galileo Study Guide by Dr. Janice Siegel
Up until Galileo’s time, people believed in the geocentric (earth in the middle) cosmological view (the composition of the universe). pre-Socratic philosophers (6th century BC) had already determined that the universe was composed of four elements: air, fire, water and earth. Aristotle (384-322 BC): joined Plato's Academy at age 17. Became tutor of Alexander in 343 BC. The greatest collector and organizer of knowledge in the ancient world. Aristotle's Universe: universe is finite and spherical, with stationary earth at center. Two sets of rules: one for earth, one for the heavenly bodies. Earth: composed of four elements fire and air (light and move upward) and earth and water (heavy, fall downwards). The Earth is in the center of all things, where heavy things fall to. Aristotle's scientific proof that the earth is a sphere: its curved shadow on the face of the moon in eclipse; the sight of stars not seen before when one travels north or south. Heavens: composed of aether - not subject to decay, immortal - just look at the perfect circular motion of celestial bodies - immutable, no beginning, no limit. Aether is outside our gritty experience and reality. (All of these suppositions will be disproven by Galileo and Kepler). Two different sets of physics laws governs the heavens and the earth. By the way, this fifth elements of aether is how the word quintessence came to be – the "true, immortal nature" of something – its core substance (quintus means "fifth" in Latin). According to Aristotle, the cosmos (universe) was a group of concentric spheres, a series of balls within balls each having the same center. Imagine a gigantic lucite ball with interior balls. The innermost ball, of course, is the earth (made of dirt). The other celestial orbs are all embedded in Crystalline spheres which revolve around the unmoving earth. You may recall that the pre-Socratic philosopher Pythagoras (530 BC) suggested that the universe worked according to mathematical principles (and boy, was he right. Just ask NASA). The ancients knew of seven planets (Neptune and Pluto cannot be seen with the naked eye) and we recall that Pythagoras (530 BC) invented the seven-tone scale (do-re-mi-fa-so-la-ti-do). The Music of the Spheres is said to ring out clear as a bell when all these crystalline spheres are in perfect harmony and aligned just right (the Age of Aquarius?) Anyway, each orb is embedded in its sphere. Here is the order of the celestial bodies revolving around the earth from nearest to farthest orbit: moon, Mercury, Venus, sun, the outer planets and last, the fixed stars. The ancients believed that all the stars of the night sky were as if white dots painted on black velvet and each night the black velvet backdrop rotated in an arc while the earth stayed motionless (well, they do all move in tandem, or together – just watch the constellations move across the sky in groups). Beyond the sphere of the fixed stars lay the "empyrean", the home of angels and immortal spirits. So much for science! Points in Favor: it certainly seems to work. If you stand in a field all day long from before sunrise, you will observe that the sun rises in the east, moves across the sky, and sets in the west and the earth doesn’t move at all. Right? The earth can’t move, or it would leave things behind, like birds and baseballs. So for 1600 years, everyone accepted this cosmological theory although it is WRONG! because THE SUN IS IN THE MIDDLE – THAT’S WHY WE CALL IT THE SOLAR SYSTEM Archimedes (287-212 BC) might have figured out the problem here, but practical applications of scientific theory were only allowed for military and agricultural purposes. Galileo notes him over 100 times in his writings. Ptolemy (100-170 AD): during time of Hadrian's rule - encouraged learning. Rejected rotation of earth because objects (like birds) would be left behind. His work, called The Almagest, was written in 150 AD and is the greatest surviving astronomical work of antiquity. Ptolemy adopted Aristotle’s model but replaced Aristotle's spheres with a system of geometric devices (equant, epicycle...) that explained the apparent motions in the heavens. (The crystalline sphere theory was rejected when they realized that comets come into the solar system at an angle and would have to break through these spheres. That's how they figured out that there really aren't solid objects up there in which the planets are enmbedded.) Ptolemy's work was the canonical work (the absolute last word) on cosmology for 14 centuries until Copernicus. MEDIEVAL EUROPE: after the fall of Rome, only Latin texts survived in the Western World (not Greek), although Plato influenced the early Christian fathers (like St. Augustine). But they were rediscovered by the Arab World and translated into Arabic and read widely. (For example, Ptolemy’s work is translated into Al-majisti). In the 9th century both Greek and Hindu scientific works were translated into Arabic (including Ptolemy's Almagest). Scholars popularized "Arabic" numbers (actually they were Hindu), and adopted the decimal system and the concept of zero. Classical learning followed in the wake of Islamic conquests that swept across North Africa then into Spain. Intellectual freedom encouraged the interaction of Islamic, Jewish, and Christian thought. During the 12th century, the ideas of Aristotle, through the influence of the pantheistic Arab philosopher Averroes, infiltrated the universities of Christendom. By the 13th century, the complete works of Aristotle were translated into Latin. The Church moved quickly. St. Thomas Aquinas (1225-1274) got the very difficult job of synthesizing Aristotelian natural philosophy with Christian theology, a revolution of religious thought. In other words, he had to make Christian thought (using the Scripture as source) jive with the older pagan understanding of the world which was taking European learning centers by storm. And he was brilliant at it. Christianity theology teaches by divine revelation – Greek philosophy puts all its stock in human wisdom. Aquinas concluded that the two were compatible. Greek natural philosophy had concluded that the earth was (a) in the middle of the universe and (b) that it was composed of different material than the rest of the universe. Aquinas agreed completely, but for very different reasons. Aquinas concluded that when God made the universe, it was absolutely perfect in every respect. His greatest achievement – man – He placed in the center, like a jewel in a crown – because He was so proud of it. But man screwed up. Because of the Fall (Adam and Eve eating the fruit of the tree of Knowledge of Good and Evil as told in Genesis 2), man sullied or dirtied the earth and everything else he touched. That is why the earth is dirty and heavy now. It used to be perfect like everything else. But everything else – all other celestial bodies – remain pristine, untouched by human hands and therefore still perfect as God made them. Aquinas therefore successfully merged Greek natural philosophy and Christian theology. The only problem was that both are based on an incorrect premise – they are wrong. And once scientific discoveries began showing that the earth was NOT in the middle, the Church panicked because they had so carefully intertwined their theological doctrine with that cosmological model that it was like a giant JENGA game – if you took that one piece out, the entire construction would come crashing down. Therefore, they made it heresy (a crime against the teachings of the church) to say that the sun was in the middle of the solar system, and not the earth. Eventually, of course, scientific discoveries would prove the earlier theory wrong, but not without casualties. Steps toward the TRUTH: COPERNICUS (1473-1543) : Because the findings of Copernicus’ text went against Church doctrine, his publisher went behind Copernicus’ back to downplay his theory, putting a special foreword in his book that caused most people to ignore the findings. (Most ironic is that Copernicus made his discoveries while working for the Church - he was trying to fix the calendar). In On The Revolutions of the Heavenly Orbs, Copernicus offers a theory based on mathematical demonstration, that the sun was at the center of the solar system and fixed stars, and that the earth was one of the planets revolving in space around IT. This suggestion of a heliocentric cosmological model (sun in the middle) helped to fix one of the worst problems associated with the Polemic model: more and more observations were being made about the movement of the celestial bodies (anything up in the sky) and more and more details weren’t being accommodated by the old model. For example: retrograde motion. You see this every day, either in your car or on the subway. When two objects running parallel to each other match in speed, object B appears to have no speed relative to object A. In other words, if you look out the car window, you can see the next lane’s car’s hubcap STOP SPINNING. It looks – for a moment – like the wheel isn’t moving at all. But then you speed ahead and his wheel STARTS MOVING BACKWARDS! Of course, it is not really moving backwards, but from your perspective it seems to be because your speed is greater than his. Well, the same thing happens with planets. Today we know that Mars and Earth have concentric (sharing the same center) orbits. We move in the same direction around the sun, but at different speeds because our orbit is shorter than Mars. Mars is visible with the naked eye, and you can easily track its movement in the evening sky. If you do track the movement of Mars, you will note that for a set number of days, Mars will appear to move ever so slightly across the sky, but then for a few days will appear in the same place, and then it will appear to move backwards. Of course, it isn’t REALLY moving backwards, any more than the car on the highway is, but from our perspective it APPEARS to be moving backwards. This makes sense to us only because we know that Mars and Earth are both moving. Imagine trying to make sense out of the hubcap that stops spinning in mid-turn if you think that you are standing on the sidewalk! The ancients (and all the way up to Galileo) thought that the Earth was in the MIDDLE and DIDN’T MOVE, so they couldn’t explain this retrograde motion at all. They added loop-de-loops called epicycles on the mapping charts, desperately trying to account for this odd planetary behavior. This caused John Milton to describe the cosmos as "with centric and concentric scribbled o'er/, cycle and epicycle, orb in orb." The problem? The EARTH IS NOT IN THE MIDDLE! But Copernicus removed the sun from the category of planets. Now he could argue – rightly – that each orb was its own center, and that in each orbit all the heavy things fell toward that center. This new system also allowed him to figure the distance from the sun of various planets, based on the time it took them to complete their revolution around it. TYCHO BRAHE (1546-1601): never accepted Copernican theory but gained more info about positions and movements of heavenly bodies. He took very detailed records of starry observations that would help Kepler later... JOHANN KEPLER (1571-1630): student of Brahe - accepted Copernicus' theory. Kepler discovered that the planets' orbits around the sun were ellipses, not perfect circles. Explained why some planets took a shorter time to make their circuit. All math: the square of the time is proportional to the cube of the distance. GALILEO: (1564-1642): first person to train a telescope on the heavens (1609). He was thus the first to realize that these "orbs" and "points of light" were substantial objects. In "The Starry Messenger" he describes his observations. One of the problems Galileo solved was how to explain how the earth could move and not leave its moon behind. This was one of the biggest arguments against scientific acceptance of the "moving earth" theory. In "The Starry Messenger," Galileo observes the moons of Jupiter, which he names the Medicean Stars to honor Cosimo de Medici. He plots the movement of the moons and concludes that they move along with the planet, which everyone agrees does move across the sky. If Jupiter can move and not lose its many moons, then Earth should have no problem keeping hold of our one Moon. Galileo also observed the moon through his telescope (he didn’t invent the telescope, but he was the first to train it on the heavens). He noticed that the moon, always thought to be perfectly spherical and without blemish, was in fact pock-marked and much like earth in many ways – it had mountains, valleys, rugged surface… and Galileo proved that it was not a luminous object – it reflected light, not produced it, as everyone thought. So why does Galileo get in trouble with the Church? 1. He agrees with the idea that the earth moves, instead of staying motionless in the center and letting other things revolve around it (like the Church says) 2. He compares the moon to the earth several times (the moon has mountains and valleys, or when he refers to a particular spot on the surface as being "about the size of Bohemia."). Church doctrine forbids any comparison between the dirty, sullied earth and the pristine and perfect heavenly bodies. 3. He usually wrote in Italian, not Latin, in order to reach the general populace. But Galileo wrote Sidereus Nuntius ("The Starry Messenger")in Latin in order to inform the scientific public of his observations and conclusions. The church feared the dissemination of such knowledge. Details of Galileo’s trial: Era: during the papacy of Pope Urban VIII. Date: June 22, 1633. Place: Santa Maria Sopra Minerva, Dominican convent in center of Rome (ironically, in a church originally dedicated to Minerva, the goddess of wisdom.) Cause: G's publication of Dialogue on the Two Principal World Systems in which he has characters argue the relative merits of Ptolemaic (Aristotelian) and Copernican cosmologies. The character arguing the Ptolemaic system comes out looking ignorant. Defense: Although Galileo had made the debater of the Church philosophy look positively stupid in his book, he claimed that in fact that it was that argument he was in agreement with. This was not a smart move and insulted his inquisitors. Verdict: "vehemently suspected of heresy"; Dialogue to be banned. Sentence: sort of probation - must repeat the penitential psalms once a week for three years - returned home to Florence within five months and eventually went blind and died after nine years of house arrest. Galileo would eventually be absolved by the Church - in 1992! in 1636, Galileo writes his famous letter to the Grand Duchess Christina, wherein he makes an eloquent argument FOR Church doctrine. In his letter he suggests that Aquinas is absolutely right - that both the scriptures AND science must come to the same conclusions about the universe and God's plan. If the two do not seem to agree, Galileo says, then the fault lies with those who have misinterpreted the Scripture. Because everything has to add up in the end. WHAT YOU NEED TO KNOW ABOUT GALILEO FOR THE EXAMINATION: Be able to explain in full: Aristotelian
(Ptolemaic) cosmological model Medicean Stars Possible essay: Why exactly does Galileo get in trouble? Be able to distinguish between Christian theology (as put forth by St. Thomas Aquinas) and Greek natural philosophy (as put forth mostly by Aristotle). Are they really reconcilable? Irreconcilable? Think about this. Can science and religion work together to unravel the mysteries of the universe? This question cannot be answered "yes" or "no" but I expect you to put some thought into it. for a tour of the
Galileo Room of the History of Science in Florence (including a peek at
Galileo's middle finger from his right hand - no kidding), go to: for a very
informative website on Galileo, including an elaborate timeline: and for really cool
pictures of the solar system (with a small section on our man): Take the Galileo quiz (put out by a publishing house hawking a Galileo book for the uninformed - warning! It's Hard!)
copyright
2001 Janice
Siegel,
All Rights Reserved
date this page was edited last:
10/25/2005 |
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