Saint Diadochos of Photiki was a fifth-century ascetic whose works are included in the Philokalia.

Symeon the New Theologian was an Eastern Orthodox monk and poet who was the last of three saints canonized by the Eastern Orthodox Church and given the title of "Theologian". "Theologian" was not applied to Symeon in the modern academic sense of theological study; the title was designed only to recognize someone who spoke from personal experience of the vision of God. One of his principal teachings was that humans could and should experience theoria.