Greek philosophers
Poseidónios
Poseidónios was a Greek philosopher, historian, geographer, astronomer and mathematician. He was born in 135 BC (Apameia, now Qalaat al-Mudiq in Syria) and died in 51 BC.
Poseidonios was one of the most versatile men of antiquity. For this reason, the lunar crater (Posidonius) is named after him.
He traveled virtually all over the Mediterranean and the Dead Sea. He sailed down the Nile, measured the height of the ocean tides in the Hispanic city of Gadir (now Cadiz), studied the behaviour of monkeys on the Moorish coast, consorted with the chiefs of the Gallic Celts, and conducted research on Vesuvius. After these travels, he became a pupil of the Stoic philosopher Panaitius in 115 BC. Around 95 BC he then founded the famous philosophical school in Rhodes. Cicero, for example, attended this school.
He served as an ambassador to Rome, and it was mainly thanks to him that Stoicism became widespread among the Roman middle and upper classes.
Together with his teacher Panaitius, he defined the idea of humanity, including the requirement that each individual should actively develop justice and love for people as an unwritten rule of human coexistence.
He was one of the first to calculate the length of the Earth's radius (but he determined it to be 5,300 kilometers, a full 1,000 kilometers less than it actually is). He is also considered the forerunner of today's anthropologists, as he studied man in various contexts.