50 Facts About Posidonius

Posidonius was considered the most learned man of his time and, possibly, of the entire Stoic school.

Posidonius settled as a teacher at Rhodes where his fame attracted numerous scholars.

Posidonius's works are now lost, but they proved a mine of information to later writers.

Posidonius sought to determine the distance and magnitude of the Sun, to calculate the diameter of the Earth and the influence of the Moon on the tides.

Posidonius, nicknamed "the Athlete", was born around 135 BC.

Posidonius was born into a Greek family in Apamea, a Hellenistic city on the river Orontes in northern Syria.

Posidonius expressed no love for his native city, Apamea, in his writings and he mocked its inhabitants.

When Panaetius died in 110 BC, Posidonius would have been around 25 years old.

In Rhodes, Posidonius maintained his own school which would become the leading institution of the time.

Around the 90s BC Posidonius embarked on a series of voyages around the Mediterranean gathering scientific data and observing the customs and people of the places he visited.

Posidonius traveled in Greece, Hispania, Italy, Sicily, Dalmatia, Gaul, Liguria, North Africa, and on the eastern shores of the Adriatic.

Posidonius wrote that daily tides are related to the Moon's orbit, while tidal heights vary with the cycles of the Moon, and he hypothesized about yearly tidal cycles synchronized with the equinoxes and solstices.

Posidonius left vivid descriptions of things he saw with his own eyes while among them: men who were paid to allow their throats to be slit for public amusement and the nailing of skulls as trophies to the doorways.

In Rhodes, Posidonius actively took part in political life, and he attained high office when he was appointed as one of the Prytaneis.

Under Posidonius, Rhodes eclipsed Athens to become the new centre for Stoic philosophy in the 1st century BC.

Posidonius was probably in his seventies at this time and was suffering from gout.

Posidonius died in his eighties in 51 BC; his grandson, Jason of Nysa, succeeded him as head of the school on Rhodes.

Posidonius was celebrated as a polymath throughout the Graeco-Roman world because he came near to mastering all the knowledge of his time, similar to Aristotle and Eratosthenes.

Posidonius attempted to create a unified system for understanding the human intellect and the universe which would provide an explanation of and a guide for human behavior.

Posidonius wrote on physics, astronomy, astrology and divination, seismology, geology and mineralogy, hydrology, botany, ethics, logic, mathematics, history, natural history, anthropology, and tactics.

Posidonius's studies were major investigations into their subjects, although not without errors.

For Posidonius, philosophy was the dominant master art and all the individual sciences were subordinate to philosophy, which alone could explain the cosmos.

Posidonius accepted the Stoic categorization of philosophy into physics, logic, and ethics.

Posidonius followed not only the earlier Stoics, but made use of the writings of Plato and Aristotle.

Posidonius studied Plato's Timaeus, and seems to have written a commentary on it emphasizing its Pythagorean features.

The philosophical grand vision of Posidonius was that the universe itself was interconnected as an organic whole, providential and organised in all respects, from the development of the physical world to the behaviour of living creatures.

Panaetius had doubted both the reality of divination and the Stoic doctrine of the future conflagration, but Posidonius wrote in favour of these ideas.

Posidonius was one of the first to attempt to prove Euclid's fifth postulate of geometry.

Posidonius suggested changing the definition of parallel straight lines to an equivalent statement that would allow him to prove the fifth postulate.

Posidonius attempted to measure the distance and size of the Sun.

Posidonius constructed an orrery, possibly similar to the Antikythera mechanism.

Posidonius's orrery, according to Cicero, exhibited the diurnal motions of the Sun, Moon, and the five known planets.

Posidonius theorized on the causes of clouds, mist, wind, and rain as well as frost, hail, lightning, and rainbows.

Posidonius estimated that the boundary between the clouds and the heavens lies about 40 stadia above the Earth.

Some of Posidonius's arguments are contested by Josephus in Against Apion.

Posidonius recorded observations on both earthquakes and volcanoes, including accounts of the eruptions of the volcanoes in the Aeolian Islands, north of Sicily.

Posidonius calculated the Earth's circumference by the arc measurement method, by reference to the position of the star Canopus.

Posidonius was informed in his approach to finding the Earth's circumference by Eratosthenes, who a century earlier arrived at a figure of 252,000 stadia; both men's figures for the Earth's circumference were uncannily accurate.

Posidonius noted that Hipparchus had added some 26,000 stadia to Eratosthenes's estimate.

Posidonius's Histories continue the account of the rise and expansion of Roman dominance, which he appears to have supported.

Posidonius did not follow Polybius's more detached and factual style, for Posidonius saw events as caused by human psychology; while he understood human passions and follies, he did not pardon or excuse them in his historical writing, using his narrative skill in fact to enlist the readers' approval or condemnation.

For Posidonius "history" extended beyond the earth into the sky; humanity was not isolated each in its own political history, but was a part of the cosmos.

Posidonius's Histories were not, therefore, concerned with isolated political history of peoples and individuals, but they included discussions of all forces and factors, which let humans act and be a part of their environment.

For example, Posidonius considered the climate of Arabia and the life-giving strength of the sun, tides, and climatic theory to explain people's ethnic or national characters.

Posidonius was the major source of materials on the Celts of Gaul and was profusely quoted by Timagenes, Julius Caesar, the Sicilian Greek Diodorus Siculus, and the Greek geographer Strabo.

Posidonius appears to have moved with ease among the upper echelons of Roman society as an ambassador from Rhodes.

Posidonius associated with some of the leading figures of late republican Rome, including Cicero and Pompey, both of whom visited him in Rhodes.

Posidonius met Pompey when he was Rhodes's ambassador in Rome and Pompey visited him in Rhodes twice, once in 66 BC during his campaign against the pirates and again in 62 BC during his eastern campaigns, and asked Posidonius to write his biography.

Posidonius fortified the Stoicism of the middle period with contemporary learning.

Today, Posidonius seems to be recognized as having had an inquiring and wide-ranging mind, not entirely original, but with a breadth of view that connected, in accordance with his underlying Stoic philosophy, all things and their causes and all knowledge into an overarching, unified world view.