The Traitor Within

One of the startsi said to his disciple, 'Watch, lest you harbour a traitor in yourself.' 'Who is the traitor?' asked the disciple. 'Self-gratification,' answered the staretz. And this is indeed so. Self-gratification is the cause of all evils. If you examine all the bad things that you have done, you will see that in each case they originated from pandering yourself.
– Theophan the Recluse, The Art of Prayer, an Orthodox Anthology