Smoke from wood kindling a fire troubles the eyes; but then the fire gives them light and gladdens them. Similarly, unceasing attentiveness is irksome; but when, invoked in prayer, Jesus draws near, He illumines the heart; for remembrance of Him confers on us spiritual enlightenment and the highest of all blessings.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
Watchfulness cleanses the conscience and makes it lucid. Thus cleansed, it immediately shines like a light that has been uncovered, banishing such darkness. Once this darkness has been banished through constant and genuine watchfulness, the conscience then reveals things hidden from us.
A certain brother asked the Abbot Poemen, saying, 'What am I to do, Father, for I am troubled in sadness?' The old man said to him, 'Look to no man for aught, condemn no man, disparage no man: and God shall give thee rest.'
Once two brethren came to a certain elder whose custom it was not to eat every day. But when he saw the brethren he invited them with joy to dine with him, saying: Fasting has its reward, but he who eats out of charity fulfills two commandments, for he sets aside his own will and he refreshes his hungry brethren.
They asked Abba Macarius, 'How should we pray?' And the old man replied, 'There is no need to speak much in prayer; often stretch out your hands and say, 'Lord, as you will and as you know, have mercy on me.' But if there is war in your soul, add, 'Help me!' and because he knows what we need, he shows mercy on us.'
We came from Palestine to Egypt and went to see one of the fathers. He offered us hospitality and we said, 'Why do you not keep the fast when visitors come to see you? In Palestine they keep it.' He replied, 'Fasting is always with me but I cannot always have you here. It is useful and necessary to fast, but we choose whether we will fast or not. What God commands is perfect love. I receive Christ in you and so I must do everything possible to serve you with love. When I have sent you on your way, then I can continue my rule of fasting. The sons of the bridegroom cannot fast while the bridegroom is with them; when he is taken away from them, then they will fast.'
A holy elder, seeing with his own eyes a certain brother fall into deep sin, not only did not judge him, but wept and said: 'He fell today; without doubt I will fall tomorrow. But he certainly will repent, whereas for myself, I am not so sure of this.'