But in the reign of the younger Andronicus, these monasteries were visited by Barlaam, [41] a Calabrian monk, who was equally skilled in philosophy and theology; who possessed the language of the Greeks and Latins; and whose versatile genius could maintain their opposite creeds, according to the interest of the moment.

The indiscretion of an ascetic revealed to the curious traveller the secrets of mental prayer and Barlaam embraced the opportunity of ridiculing the Quietists, who placed the soul in the navel; of accusing the monks of Mount Athos of heresy and blasphemy.

His attack compelled the more learned to renounce or dissemble the simple devotion of their brethren; and Gregory Palamas introduced a scholastic distinction between the essence and operation of God.

His inaccessible essence dwells in the midst of an uncreated and eternal light; and this beatific vision of the saints had been manifested to the disciples on Mount Thabor, in the transfiguration of Christ.

Yet this distinction could not escape the reproach of polytheism; the eternity of the light of Thabor was fiercely denied; and Barlaam still charged the Palamites with holding two eternal substances, a visible and an invisible God.