Geocentric model that both Venus and Mercury went around the Sun rather than the Earth, but this is no longer accepted. Martianus Capella definitely put Mercury and Venus in orbit around the Sun. Aristarchus of Samos was the most radical. He wrote a work, which has not survived, on heliocentrism, saying that the Sun was at the center of the universe, while the Earth and other planets revolved around it. His theory was not popular, and he had one named follower, Seleucus of Seleucia. In 1543, the geocentric system met its first serious challenge with the publication of Copernicus' "De revolutionibus orbium
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