Be aware of pride; it is blasphemy against God in His gifts and it makes the sinner bold. If you were truly humble you would understand what I am trying to say. Contemplative prayer is God’s gift, wholly gratuitous. No one can earn it. It is the nature of this gift that one who receives it receives also the aptitude for it. No one can have this attitude without the gift itself. The aptitude for this work is one with the work; they are identical. He who experiences God working in the depths of his spirit has the aptitude for contemplation and no one else. For without God’s grace a person would be so completely insensitive to the reality of contemplative prayer that he would be unable to desire or long for it. You possess it to extent that you will and desire to possess it, no more and no less. But you will never desire to possess it until that which is ineffable and unknowable moves you to desire the ineffable and unknowable. Do not be curious to know more. I beg you. Only become increasingly faithful to this work until it becomes your whole life. –‘Cloud of Unknowing’ 34

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Vainly considering himself clever and sophisticated about the spiritual life, it is not long before he begins to interpret what he hears in literal, material terms, entirely missing the deeper spiritual meaning. And so he foolishly strains his physical and emotional resources beyond reason. Neglecting the inspiration of grace and excited by vanity and conceit, he strains his endurance so morbidly that in no time he is weary and enervated in body and spirit. Then he feels the necessity to alleviate the pressure he has created by seeking some empty material or physical compensation as a relaxation for mind and body.

…spiritual blindness and the abuse he inflicts on his body in this pseudo-contemplation (for it can hardly be called spiritual) may lead him to arouse his passions unnaturally or work himself into a frenzy. And all this is the result of pseudo-spirituality and maltreating the body. It is instigated by his enemy, the fiend, who takes advantage of his pride, sensuality, and intellectual conceit to deceive him.

Yet unfortunately, these people believe that the excitement they feel is the fire of love kindled in their breasts by the Holy Spirit. From this deception and the like springs evil of every kind, much hypocrisy, heresy, and error. For this sort of pseudo-experience brings with it the false knowledge of the fiend’s (Satan’s) school just as an authentic experience brings with it understanding of the truth taught by God. Believe me when I say that the devil has his contemplatives as surely as God has his. –‘Cloud of Unknowing’ 45