Letters of Saint Ambrose of Optina. Letter 243.
Praise and thanksgiving to the Lord for due to all-powerful petitions and prayer intercession of Our Lady Blessed Virgin Mary your gloomy thoughts at least were somewhat cleared up. Although the desire to move to Arz. does not leave you, sometimes the thought contradicts you, and the secret suggestion in the heart says that this intention and desire is vain.
You write that the suggestion is very quiet and calm, but on the contrary, when the desire to leave the monastery seizes you, you feel bitterness, gloom, unforgiveness, and hatred against neighbors, and laziness in prayer. You should understand from this that the desire is from the devil, and it is a suggestion of the enemies and haters of the human race, looking for our eternal damnation. Saint Gregory of Sinai writes: "You need great discrimination in order to distinguish between good and evil. ... You must also be aware that the effects of grace are self-evident, and that even if the devil does transform himself he cannot produce these effects: he cannot induce you to be gentle, or forbearing, or humble, or joyful, or serene, or stable in your thoughts; he cannot make you hate what is worldly, or cut off sensual indulgence and the working of the passions, as grace does. He produces vanity, haughtiness, cowardice and every kind of evil." (citation from Philokalia, Vol. 4).
You partly experienced this yourself, by your own experience, so be careful and reasonable: keep the good, and reject the evil. You write that sometimes some kind of painful, untamed, disheveled, fierce, devilish joy comes over you, that tires you awfully, and that every sorrow of the soul is better than this ugly joy. Now you see for yourself that this joy is from the enemy: but at the same time you should know that this disheveled joy does not come without cause, and, apparently, it was once that you accepted the deceptive and delusional joy as a true one because of inexperience and negligence.
I likewise advise you to sit at home, in the monastery, and in your cell this year, and to go nowhere. God knows how much your life will last, and therefore, especially in recent times, you should not despise the secret suggestions of our conscience, aroused by the Guardian Angel, given to us at Baptism. Not in vain the ancient fathers said: "Sit in your cell, and it will teach thee all". Especially that befits a person, who is weak, both bodily and mentally. Now wandering and physical works are inappropriate in time and place. Old men and women don’t go to the children's school as it is inappropriate and untimely for them due to their weakened memory and physical strength. It is appropriate for old and weak to humble themselves and to prepare themselves with sincere repentance to go to eternity.