Editing Posidonius (section)

===Travels===
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.<ref name="sellars10"/> He traveled in Greece, [[Hispania]], Italy, [[Sicily]], [[Dalmatia]], [[Gaul]], [[Liguria]], [[North Africa]], and on the eastern shores of the [[Adriatic]].<ref name=Britannica/>

In [[Hispania]], on the Atlantic coast at Gades (the modern [[Cadiz]]), Posidonius could observe tides much higher than in his native Mediterranean.<ref>{{Cite book |last=Russell |first=Bertrand |title=A History of Western Philosophy |year= 1946 |publisher= Simon and Schuster|isbn= 978-1-4165-9915-9|page= |url=https://books.google.com/books?id=iQZ6Xk9VdtAC&q=Russell+history+of+western+philosophy |access-date=4 November 2023 |chapter=28| author-link= Bertrand Russell}}</ref> He 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.<ref name="kiddc13">{{Harvnb|Kidd|1999|p=13}}</ref>

In [[Gaul]], he studied the [[Celt]]s.<ref name="kiddc4"/> He left descriptions of customs such as nailing skulls to doorways as trophies, which he witnessed,<ref>Posidonius, fragment 55 (quoted by [https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Strabo/4D*.html#4.5 Strabo, Book 4]).</ref> and vivid legends told to him by the Celts, such as a story that in the past, men were paid to allow their throats to be slit for public amusement.<ref>Posidonius, fragment 16 (quoted by [http://www.attalus.org/old/athenaeus4.html#154 Athenaeus, Book 4])</ref> But he noted that the Celts honored the [[Druids]], whom Posidonius saw as philosophers, and concluded that, even among the barbaric, "pride and passion give way to wisdom, and Ares stands in awe of the Muses." Posidonius wrote a geographic treatise on the lands of the [[Celt]]s which has since been lost, but which is referred to extensively (both directly and otherwise) in the works of [[Diodorus Siculus|Diodorus of Sicily]], [[Strabo]], [[Julius Caesar|Caesar]] and [[Tacitus]]' ''[[Germania (book)|Germania]]''.