I wish to address my speech to each one of those who attach themselves to the vanity of things present. Tell me, how can you say, “I understand it all, I am mortal, and visible things are a shadow and death comes unexpectedly, the glory of the righteous is eternal and the disgrace of sinners has no end,” and yet you do not renounce evil things? If you really see, how is it that you stumble like a blind man and your whole body and soul are covered with black marks? If you know what is good, how is it that you do evil, as though you did not know? If you know that all visible things are a shadow and all pass away, are you not ashamed of playing with shadows and hoarding transitory things? Like a child you draw water with a bucket full of holes; do you not realize it and take it into account, my dear friend? As though there were nothing more serious than appearance and illusion, as though reality has been taken from them?
St Symeon the New Theologian. Discourse 19 § 5