The Letters of Saint Ambrose of Optina.
On the harmful effects of improper prayer, and that the inconceivable Divinity should not be imagined.
Venerable in the Lord Brother D.
I have received your letter. You suffered the described infirmities of mind and body because you, for inexperience, used the wrong way of prayer, rising with the nous to the throne of the Holy Trinity and contemplating the inconceivable Divinity under the human representation, in the image and likeness, what by the words of St. Gregory of Sinai and Symeon the New Theologian, leads the inexperienced ones to delusion. The method of the prayer, with the vision and elevation of the mind to Heaven, can only be used by the passionless ones, who have cleansed themselves from the admixture of passions by means of deeds for a long time and especially through humility and with God's help; but it is dangerous for the inexperienced and infirm, it leads to demonic delusion when people undergo improper infirmities and passions, as the Saint Apostle explains this: “And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient”(Romans 1: 28).
Visions that you had and saw, such as a vision of the risen Lord, the vision of the Mother of God, and other similar ones, are untrue. Do not believe any further dreams or visions. All this is dangerous and beguiling, and not crowned with a good ending. The very fruits of your present life may serve you as a clear proof that you were deceived and carried away by the self-conceit with the experienced visions, and the imaginary purity, and lightness of mind, and the incidence of tears, and tenderness. All of this nourished your secret and subtle arrogance, and the enemy delusion, what led to bitter fruits afterwards. However, you should not despair. There is no sin that overcome the love of God to men. The Lord is strong to improve your soul's circumstances, if you endeavour to lay the new foundation with true repentance and sincere humility. Put away the former way of praying and do not dare to lift the mind to Heaven and imagine the inconceivable Divinity. You should reverently worship the image of the Holy Trinity on the icon, but not imagine the Divinity in the mind this way – it is dangerous, according to the teaching of the Holy Fathers - Gregory of Sinai and others. There is no possibility to enlarge on these things now for the lack of time. If you want to right the matter, you should follow the prayer of the tax collector, who, by the words of the Lord Himself, didn’t dare even to raise his eyes to Heaven, not to mention his mind i.e. did not dare to elevate his mind to Heaven and stood before God with fear and humility, as seen by the Lord from above, and asking for mercy: God be merciful to me a sinner (Luke 18: 13), and not daring to argue with the Pharisee, who clearly humiliated him. Here is an example of repentance and return to the right path for all who have sinned. And you shouldn’t teach and argue with anyone, and give heed only to your repentance and your own life, in awe of God, with humility and self-reproach, not justifying yourself and not rejecting reproaches of others, especially not judging and not condemning anyone.