Patriarch Callistus and Ignatius of Xanthopoulos. "Directions to hesychasts, in a hundred chapters".
73. More on imaginings and fantasies of the mind, and on the distinctive Signs of prelest and of truth
The signs of prelest
Keeping silence and wishing to be alone with the one God, if you see something sensory or mental, whether within or without - such as the face of Christ, or of an angel, or the image of a saint, or some radiant image dreamed of by the mind - never accept it, but indignantly refuse to believe in it, even if it is good, until you have questioned someone with experience. Such behaviour is the most practical, profitable and pleasing to God. Always keep your mind empty of colour, image, form, appearance, quality or quantity, solely listening to the words of the prayer, learning from them and pondering over them in an inner movement of the heart, thus following St. John of the Ladder who says: 'The beginning of prayer is to banish oncoming thoughts as soon as they appear. Its middle stage is to keep the mind contained in the words we say or think. The perfection of prayer is ravishment to the Lord' (Ch. 28). St. Nilus speaks of it thus: 'The highest prayer of the perfect is the ravishment of the mind and its total transcendence of everything sensory, when "the Spirit itself maketh intercession for us with groanings which cannot be uttered" (Rom. viii. 26), before God, Who sees our heart like an open book, intimating its desire by the soundless signs written therein. Thus St. Paul was "caught up to the third heaven", "whether in the body, I cannot tell; or whether out of the body, I cannot tell" (2 Cor. xii. 2). Thus "Peter went up upon the housetop to pray" and saw a vision (Acts x. 9 ). The stage of prayer which comes second to this higher prayer, is when the words are pronounced with a contrite mind following the words, conscious of Him to Whom it sends its prayer. But a prayer interrupted by cares of the flesh and mixed with them is far from a level becoming to one who prays.' Abide in this and accept nothing else until your passions are subdued, always questioning the experienced, as has been said. These are the signs of prelest.