“Be attentive to yourself,” says Moses (Deuteronomy 15:9 LXX)–that is, to the whole of yourself, not to a few things that pertain to you, neglecting the rest. By what means? With the intellect assuredly, for nothing else can pay attention to the whole of yourself. Set this guard, therefore, over your soul and body, for thereby you will readily free yourself from the evil passions of body and soul. Take yourself in hand, then, be attentive to yourself, scrutinize yourself; or rather, guard, watch over the test yourself, for in this manner you will subdue your rebellious unregenerate self to the Spirit and there will never again be “some secret iniquity in your heart” (Deuteronomy 15:9).
If, says the Preacher, the spirit that rules over the evil demons and passions rises up against you, do not desert your place (cf. Ecclesiastes 10:4)–that is to say, do not leave any part of your soul or body unwatched. In this way you will master the evil spirits that assail you and you will boldly present yourself to Him who examines hearts and minds (cf. Psalms 7:9); and He will not scrutinize you, for you will have already scrutinized yourself. As St Paul says, “If we judged ourselves we would not be judged” (1 Corinthians 11:31).
~St Gregory Palamas (Philokalia, vol.4, pp.338-339)