Byzantine monk and mystic, termed the New Theologian to mark his difference from two key figures in Greek Christian esteem, St. John the Evangelist and the 4th-century theologian St. Gregory of Nazianzus. Through his spiritual experiences and writings Symeon prepared the way for Hesychast (Hesychasm) mysticism, a 14th-century Eastern movement in contemplative prayer.

Oriented early toward monastic contemplation, Symeon became abbot of the monastery of St. Mamas, near Constantinople, about 980. He was compelled to resign this office in 1009 and retire to Chrysopolis because of his austere monastic policy and a dispute with the Patriarch of Constantinople over methods of spirituality, especially his devotion to his former monk tutor, Symeon the Studite.

Symeon the New Theologian's writings consist mainly of catecheses (Greek: “doctrinal and moral instructions”); sermons preached to his monks at St. Mamas; a series of short rules, capita (Latin: “chapters”); and the Hymns of the Divine Loves, describing his spiritual experiences. Symeon's mystical theology is a distinct phase of an evolutionary process in Greek spirituality that began in the late 2nd century. Its central theme is the conviction that, by applying the classical methods of mental prayer, one experiences a contemplative “vision of light,” a symbolic term denoting the intuitional illumination that the mystic realizes in his encounter with the Divine Unknown. Symeon emphasized that such experience is attainable by all who earnestly immerse themselves in the life of prayer and is essential to interpreting sacred Scriptures.