Published in 1628, On the Motion of the Heart and Blood was written by English physician William Harvey. In the treatise, Harvey introduces the doctrine of the circulatory system. He asserts that blood is pumped from the heart to the extremities, and then the blood returns from the extremities to the heart in a circular fashion. Continue reading HARVEY: The Motion of the Heart and Blood
The first sentence of Dante’s Divine Comedy is, “Midway in our life’s journey, I went astray from the straight road and woke to find myself alone in a dark wood.” In other words, the Divine Comedy is a product of Dante’s mid-life crisis. He is disappointed in the life he has led thus far. He has an existential crisis and asks himself the “big question” – how should one live? Continue reading DANTE: The Divine Comedy [Hell]
75 – In Question 75, Aquinas argues that the human soul is incorporeal because corporeal bodies are not the principle of life, else all bodies would be alive. We see that only bodies imbued with an incorporeal soul have life. This argument presupposes that a certain arrangement of well-functioning physical bodies cannot animate a body. Continue reading ST. THOMAS AQUINAS: Summa Theologica [Part I, QQ 75-76, 78-79]
Plotinus is an ancient Greek philosopher who lived from 205-270 BC. He belongs to the philosophical school of Neoplatonism, which expanded upon the metaphysical concepts of Plato. In the Sixth Ennead, Plotinus discourses on the nature of Being, and the nature of the One in particular. The One is Plato’s Form of the Good. It is that from which all existence is derived. Plotinus writes that defining the One is impossible. We must intuit its existence. In order to accomplish this union with the One, we must lead an ascetic life, in which we take little heed of the body and we focus our attention on metaphysical truths. Plotinus’ thoughts have had a significant role in the formation of Christian thought, which has dominated the West for several millennia. Continue reading PLOTINUS: Sixth Ennead
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.