The Conferences Of John Cassian by John Cassian
Chapter VIII. How it is given to but few to understand what sin is.
Those on the other hand who make the sum of all their joy and delight and bliss consist in the contemplation of divine and spiritual things alone, if they are unwillingly withdrawn from them even for a short time by thoughts that force themselves upon them, punish this as if it were a kind of sacrilege in them, and avenge it by immediate chastisement, and in their grief that they have preferred some worthless creature (to which their mental gaze was turned aside) to their Creator, charge themselves with the guilt (I had almost said) of impiety, and although they turn the eyes of their heart with the utmost speed to behold the brightness of the Divine Glory, yet they cannot tolerate even for a very short time the darkness of carnal thoughts, and execrate whatever keeps back their soul's gaze from the true light. Finally when the blessed Apostle John would instill this feeling into everybody he says: |Little children, love not the world, neither the things which are in the world. If any man love the world, the love of God is not in him: for everything that is in the world is the lust of the flesh and the lust of the eyes and the pride of life, which is not of the Father but of the world. And the world perisheth and the lust thereof: but he that doeth the will of God abideth forever.| The saints therefore scorn all those things on which the world exists, but it is impossible for them never to be carried away to them by a brief aberration of thoughts, and even now no man, except our Lord and Saviour, can keep his naturally wandering mind always fixed on the contemplation of God so as never to be carried away from it through the love of something in this world; as Scripture says: |Even the stars are not clean in His sight,| and again: |If He puts no trust in His saints, and findeth iniquity in His angels,| or as the more correct translation has it: |Behold among His saints none is unchangeable, and the heavens are not pure in His sight.|