We should watch over and guard our heart in the following manner:
When an evil recollection crops up in our mind through demonic
deviousness, we must banish it from our heart immediately because if we
dwell on this thought, the devil who lures us into evil may drag and throw
us down a cliff of detrimental, dirty thoughts.
Even the commandment given to the first created man by God
commands that we crush the head of the serpent (Gen. 3:15); that is, the
beginning of harmful thoughts with which this snake attempts to slither into
our soul. Otherwise, if we accept the head, which is the beginning of the
evil thought, we will in turn accept the remainder of the snake's body as
well; that is, we will consent to the sinful pleasure, which will in turn plunge
our mind into the sinful action.
We must, according to the Scriptures, destroy all the evil on the
earth every morning (Ps. 100:8). In other words, using the light of
knowledge, we must detect and destroy sinful thoughts from the earth,
which is our heart according to the teaching of the Lord. And while the
sons of Babylon (that is, the evil thoughts) are still infants, we must smash
them to the ground and shatter them on the rock—the rock being Christ
(Ps. 136:9). Otherwise, if we allow these infant thoughts to develop and
become grown men, we will not be able to defeat them without a
tremendous amount of pain and effort.
(St. John Cassian
When you find yourself at the beginning of an evil, don't think: "This
won't conquer me." The very fact that you have entered within the
boundaries of evil is an indication that you have already been conquered.
Everything starts off small, and gradually it develops and increases.
The strategy of evil is like an intricate web; whoever has been
caught in it —even a little—becomes completely entangled, if he is not
careful.
(St. Mark the Ascetic)
