Symeon 1 was a leader of the Paulicians; he was an imperial official (βασιλικόν τινα), sent by the emperor (unnamed, but probably Constantine IV or Justinian II) to stone the heretic Konstantinos 1 to death and to convert his followers back to Christianity; accompanied by a local official, Tryphon 1, he met the Paulicians near Koloneia and ordered them to stone Konstantinos 1; they refused but eventually Ioustos 2, Konstantinos 1's adopted son, obeyed; Symeon 1 proceeded to punish the disciples of Konstantinos 1 but at the same time he learned more about the beliefs of the heretics; Symeon 1 then returned to court but three years later left secretly and returned to Kibossos (a fort near Koloneia), assembled the surviving disciples of Konstantinos 1 and became his successor as leader of the heresy, adopting the name Titos; Peter of Sicily proposed to call him Ketos instead; three years later Symeon 2 and Ioustos 2 disagreed over the interpretation of a statement of St Paul; Ioustos 2 approached the bishop of Koloneia (unnamed) for his interpretation but in doing so disclosed details of the sect and its heresy; the bishop informed the emperor, who was Justinian II (Ioustinianos 1), and after an investigation all who failed to repent (including perhaps Symeon 1, who is not mentioned again) were burnt; Symeon 1 continued the building of the church of "Macedonia" (meaning Kibossos), begun by Konstantinos 1: Peter of Sicily, 103-111.

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