Geocentric model knew about Tusi's work or that of the Maragha school. Not all Greeks agreed with the geocentric model. The Pythagorean system has already been mentioned; some Pythagoreans believed the Earth to be one of several planets going around a central fire. Hicetas and Ecphantus, two Pythagoreans of the 5th century BC, and Heraclides Ponticus in the 4th century BC, believed that the Earth rotated on its axis but remained at the center of the universe. Such a system still qualifies as geocentric. It was revived in the Middle Ages by Jean Buridan. Heraclides Ponticus was once thought to have proposed
Truce term credibility". "Pax" was no longer a group word as reported by the Opies. Other terms reported included "pips", "force field" and "quits". The authors concluded that either the Opies had grossly oversimplified the picture or things had radically changed in 30 years (some seven to eight generations of primary school children). They also noted that although some schools reported a marked preference for a particular term, all schools reported at least some children using different terms. The Concise Scots Language Dictionary published in 1999, records the use of "keys" as a truce term in Fife, south west and west central