Saints Barsanuphius and John. "Guidance Toward Spiritual Life."
Q: I have heard that if one and the same dream appears to someone three times, one should recognize it as true; is this so, my Father?
A: No, this is wrong; such a dream also one need not believe. He who has appeared once to anyone falsely can do this three times and more. Watch, lest you be put to shame (by the demons), but pay heed to yourself, brother.
Q: Tell me, Master, how can the devil dare in a vision or a fantasy during sleep to show the Master Christ or Holy Communion?
A: He cannot show the Master Christ Himself, nor Holy Communion, but he lies and presents the image of some man and simple bread; but the holy Cross he cannot show, for he does not find means of depicting it in another form.
Inasmuch as we know the true sign and image of the Cross, the devil does not dare to use it (for our deception); for on the Cross his power was destroyed, and by the Cross a fatal wound was given him. The Master Christ we cannot recognize by the flesh, which is why the devil tries to convince us by lying that it is He, so that having believed the deception as if it were truth, we might perish. And thus, when you see in a dream the image of the Cross, know that this dream is true and from God; but strive to receive an interpretation of its significance from the Saints, and do not believe your own idea. May the lord enlighten the thoughts of your mind, O brother, so that you might escape every deception of the enemy.