Monad (philosophy)The term monad () is used in some cosmic philosophy and cosmogony to refer to a most basic or original substance. As originally conceived by the Pythagoreans, the Monad is the Supreme Being, divinity or the totality of all things. According to some philosophers of the early modern period, most notably Gottfried Wilhelm Leibniz, there are infinite monads, which are the basic and immaterial elementary particles, or simplest units, that make up the universe.
Alcmaeon of CrotonAlcmaeon of Croton (ælkˈmiːɒn; Ἀλκμαίων ὁ Κροτωνιάτης, Alkmaiōn, gen.: Ἀλκμαίωνος; fl. 5th century BC) was an early Greek medical writer and philosopher-scientist. He has been described as one of the most eminent natural philosophers and medical theorists of antiquity and he has also been referred to as "a thinker of considerable originality and one of the greatest philosophers, naturalists, and neuroscientists of all time." His work in biology has been described as remarkable, and his originality made him likely a pioneer.
CalcidiusCalcidius (or Chalcidius) was a 4th-century philosopher who translated the first part (to 53c) of Plato's Timaeus from Greek into Latin around the year 321 and provided with it an extensive commentary. This was likely done for Bishop Hosius of Córdoba. Very little is otherwise known of him. His translation of the Timaeus was the only extensive text of Plato known to scholars in the Latin West for approximately 800 years. His commentary also contained useful accounts of Greek astronomical knowledge.
HippasusHippasus of Metapontum (ˈhɪpəsəs; Ἵππασος ὁ Μεταποντῖνος, Híppasos; c. 530 – c. 450 BC) was a Greek philosopher and early follower of Pythagoras. Little is known about his life or his beliefs, but he is sometimes credited with the discovery of the existence of irrational numbers. The discovery of irrational numbers is said to have been shocking to the Pythagoreans, and Hippasus is supposed to have drowned at sea, apparently as a punishment from the gods for divulging this.
TetractysThe tetractys (τετρακτύς), or tetrad, or the tetractys of the decad is a triangular figure consisting of ten points arranged in four rows: one, two, three, and four points in each row, which is the geometrical representation of the fourth triangular number. As a mystical symbol, it was very important to the secret worship of Pythagoreanism. There were four seasons, and the number was also associated with planetary motions and music.
Commentaries on AristotleCommentaries on Aristotle refers to the great mass of literature produced, especially in the ancient and medieval world, to explain and clarify the works of Aristotle. The pupils of Aristotle were the first to comment on his writings, a tradition which was continued by the Peripatetic school throughout the Hellenistic period and the Roman era. The Neoplatonists of the late Roman empire wrote many commentaries on Aristotle, attempting to incorporate him into their philosophy.
Thierry of ChartresThierry of Chartres (Theodoricus Chartrensis) or Theodoric the Breton (Theodericus Brito) (died before 1155, probably 1150) was a twelfth-century philosopher working at Chartres and Paris, France. The cathedral school at Chartres promoted scholarship before the first university was founded in France. Thierry was a major figure in twelfth-century philosophy and learning, and, like many twelfth-century scholars, is notable for his embrace of Plato's Timaeus and his application of philosophy to theological issues.
Commensurability (mathematics)In mathematics, two non-zero real numbers a and b are said to be commensurable if their ratio a/b is a rational number; otherwise a and b are called incommensurable. (Recall that a rational number is one that is equivalent to the ratio of two integers.) There is a more general notion of commensurability in group theory. For example, the numbers 3 and 2 are commensurable because their ratio, 3/2, is a rational number. The numbers and are also commensurable because their ratio, , is a rational number.
HicetasHicetas (Ἱκέτας or Ἱκέτης; c. 400 – c. 335 BC) was a Greek philosopher of the Pythagorean School. He was born in Syracuse, Magna Graecia. Like his fellow Pythagorean Ecphantus and the Academic Heraclides Ponticus, he believed that the daily movement of permanent stars was caused by the rotation of the Earth around its axis. When Copernicus referred to Nicetus Syracusanus (Nicetus of Syracuse) in De revolutionibus orbium coelestium as having been cited by Cicero as an ancient who also argued that the Earth moved, it is believed that he was actually referring to Hicetas.
Copernican RevolutionThe Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar System. This revolution consisted of two phases; the first being extremely mathematical in nature and the second phase starting in 1610 with the publication of a pamphlet by Galileo.
