The Cloud of Unknowing, ed. by Evelyn Underhill, , at sacred-texts.com
That a worker in this work should not deem nor think of another worker as he feeleth in himself.
LO! hereby mayest thou see that he that may not come for to see and feel the perfection of this work but by long travail, and yet is it but seldom, may lightly be deceived if he speak, think, and deem other men as he feeleth in himself, that they may not come to it but seldom, and that not without great travail. And on the same manner may he be deceived that may have it when he will, if he deem all other thereafter; saying that they may have it when they will. Let be this: nay, surely he may not think thus. For peradventure, when it liketh unto God, that p. 304 those that may not at the first time have it but seldom, and that not without great travail, sithen after they shall have it when they will, as oft as them liketh. Ensample of this we have of Moses, that first but seldom, and not without great travail, in the mount might not see the manner of the Ark: and sithen after, as oft as by him liked, saw it in the Veil. p. 305