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.
Prayer demands that the mind should be pure of all thought and should admit nothing not belonging to prayer, even if it were good in itself. As if inspired by God the mind should withdraw from all things and hold its converse with Him alone.
Do not pray that things may be according to your desires, for they are not always in keeping with the will of God. Better pray as you were taught, saying: ‘Thy will be done’ on me (Matt. vi 10). And ask thus about all things, for He always desires what is good and profitable for your soul, whereas you do not always seek it.
Do not rail against anyone, but rather say ‘God knows each one.’ Do not agree with him who slanders, do not rejoice at his slander and do not hate him who slanders his neighbor. This is what it means not to judge.
Be fond of working with your hands, but still more of the memory of prayer; because the first does not always bring us the fruit of that occupation, while the second does so unceasingly. Do not stop praying until you have paid your due of prayer in full, and do not listen to the thought that it is time to sit down to work. Equally, when you sit at work, do not be too concerned in it, lest you agitate the heart by your haste and make it worthless for prayer.
Pray firstly to be purified of passions, secondly to be freed from ignorance and forgetfulness, and thirdly to be delivered from all temptation and forsaking.
