Do not neglect the practice of the virtues; if you do, your spiritual knowledge will decrease, and when famine occurs you will go down into Egypt (Genesis 41:57, 46:6).
No Christian believing rightly in God should ever be off his guard. He should always be on the look-out for temptation, so that when it comes he will not be surprised or disturbed, but will gladly endure the toil and affliction it causes, and so will understand what he is saying when he chants with the prophet: 'Prove me, O Lord, and try me' (Ps. 26:2 LXX). For the prophet did not say, 'Thy correction has destroyed me,' but, 'it has upheld me to the end' (Ps. 18:35 LXX).
In this order, and by this succession, the ecclesiastical tradition from the apostles, and the preaching of the truth, have come down to us. And this is most abundant proof that there is one and the same vivifying faith, which has been preserved in the Church from the apostles until now, and handed down in truth.
Brothers, as long as you have breath in your bodies, strive for your salvation. Before the hour comes in which we shall weep for ourselves, let us practice virtue eagerly. For I tell you that if you knew what good things are in heaven, what promise is laid up for the saints and how those who have fallen away from God are punished and also what torments are laid up for those who have been negligent – especially those who have known the truth and have not led a way of life worthy of it so as to inherit that blessedness which is reserved for the saints and to flee the punishments of these torments – then you would endure every pain in order to be made perfect in the virtue which is according to Christ.
Go to the tombs and see that the assurance of men is nothing. Why then does man who is dust indulge in vainglory? Why does he who is all stench exalt himself? Let us therefore weep for ourselves while we have time, lest, at the hour of our departure, we be found asking God for extra time to repent.
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.
