A monk is a man who has freed his intellect from attachment to material things and by means of self-control, love, psalmody and prayer cleaves to God.

He who has renounced such things as marriage, possessions and other worldly pursuits is outwardly a monk, but may not yet be a monk inwardly. Only he who has renounced the impassioned conceptual images of these things has made a monk of the inner self, the nous.

It is easy to be a monk in one's outer self if one wants to be; but no small struggle is required to be a monk in one's inner self.

St Maximos the Confessor