“…these same virtues [ascetical practices like fasting, prostrations, etc.]  may do more harm than their open omission to those who take them as the sole basis of their life and their hope…and when they pay attention only to the external practice of those virtues, and leave their heart to be moved by their own volitions and the volitions of the devil… Thinking of their external and pious works and deeming them good, they imagine that they have already reached perfection and, puffing themselves up, begin to judge others.”

(St Nikodemos of the Holy Mountain)