Admission into the community was completed with a handshake with the "pater", just as Mithras and Sol shook hands. The initiates were thus referred to as "syndexioi" (those united by the handshake). The term is used in an inscription by Proficentius and derided by Firmicus Maternus in "De errore profanarum religionum", a 4th century Christian work attacking paganism. In ancient Iran, taking the right hand was the traditional way of concluding a treaty or signifying some solemn understanding between two parties.