Johannes Kepler published Book IV of the Epitome of Copernican Astronomy in 1617. In Book IV, Kepler formally presents his three laws of planetary motion that resolve the problems associated with the epicycles of Copernicus’ heliocentric model. Kepler’s First Law is called the Law of Ellipses. It states that “the orbits of the planets are ellipses, with the Sun at one focus.” Kepler’s Second Law is called the Law of Equal Areas in Equal Time. It states that “the line between a planet and the sun sweeps out equal areas in the plane of the planet’s orbit over equal times.” Kepler’s Third Law is called the Law of Harmony. It states that “the time required for a planet to orbit the sun, called its period, is proportional to half the long axis of the ellipse raised to the 3/2 power.” Although Kepler discovered these Laws, he did not know how they worked. Newton solved this problem with his Theory of Gravity.
Nicolaus Copernicus published the Revolutions of the Heavenly Spheres in 1543. In Book I, Copernicus presents his heliocentric model of the universe. He argues that the Sun, not the Earth, is the center of the universe. He also correctly determined the order of the planets. He wrote that the planets revolve around the Sun in the following spheres – Mercury, Venus, Earth, Mars, Jupiter, and Saturn. However, he stubbornly held onto the belief that the planets must revolve around the sun in perfect circles; for God is perfect. This caused him to mistakenly retain Ptolemy’s system of epicycles to explain the motions of the heavens. Continue reading COPERNICUS: Revolutions of the Heavenly Spheres [Introduction—Book I-Ch. 11]
In The Almagest, Ptolemy outlines antiquity’s geocentric model of the universe. The model is based on the assumptions that the universe is spherical, the Earth is a sphere, the Earth is at the center of the universe, and the Earth does not move. Although modern scientific advances have determined that many of these assumptions are false, Ptolemy correctly conjectures that the Earth is spherical (and yes, I know that the Earth is not a perfect sphere) which is an accomplishment considering that Ptolemy wrote The Almagest in 150 AD, a time when modern astronomical observation instruments were unavailable.
Sinon Proves the Tongue is Mightier Than the Sword
In the Aeneid, Virgil tells the story of Aeneas, a Trojan warrior who fled Troy while the Greeks “burnt the topless towers of Illium.” After fleeing the city, Aeneas sets sail and lands in Carthage, a city located in Northern Africa. There, Dido, the Queen of Carthage, hosts a banquet in honor of the Trojans. At the banquet, Aeneas recounts the sad story related to Troy’s destruction. Through Aeneas’ reminiscence, Virgil describes how the power of words ultimately precipitated Troy’s downfall.
Continue reading VIRGIL: The Aeneid
Galen lived in the Roman Empire during the late 100s AD. He is primarily known for his contributions to medicine, especially for his refinement of the Hippocratic theory of the four humors. Continue reading GALEN: On the Natural Faculties
Hippocrates is known as the “Father of Medicine.” Although many of his medical claims have been proven false, his approach to medicine was revolutionary, and it has endured to the present day. He sought for the causes of disease in natural things, such as the weather, a person’s diet, and a person’s genetics. This is a radical departure from the previous belief that illness was a punishment sent from the gods. Continue reading HIPPOCRATES: The Oath; On Ancient Medicine; On Airs, Waters, and Places; The Book of Prognostics; Of the Epidemics; The Law; On the Sacred Disease
Aristotle claims that the soul is the form and essence of all living things. The soul is composed of many parts. All living things – plants and animals – possess a soul with a generative part, which is responsible for the nutrition and reproduction of living beings. Only animals possess a soul with a sensitive part, which enable the animal to feel pleasure and pain. Some animals possess other senses such as sight, smell, and taste. Finally, only man possess a soul with the ability to think. Continue reading ARISTOTLE: On the Soul [Book II, Ch. 1-3; Book III]