"I entreat you not to leave your heart unguarded, so long as you are in the body. Just as a farmer cannot feel confident about the crop growing in his fields, because he does not know what will happen to it before it is stored away in his granary, so a man should not leave his heart unguarded so long as he still has breath in his nostrils. Up to his last breath he cannot know what passion will attack him; so long as he breathes, therefore, he must not leave his heart unguarded, but should at every moment pray to God for His help and mercy."
- St Isaiah the Solitary
Reference: The Philokalia: the complete text By Saint Nicodemus (the Hagiorite), Saint Makarios (Metropolitan of Corinth), Gerald Eustace Howell Palmer