Understand me. It is so simple. People who do not know God, or who go against Him, are to be pitied; the heart sorrows for them and the eye weeps. Both paradise and torment are clearly visible to us: We know this through the Holy Spirit. And did not the Lord Himself say, 'The kingdom of God is within you?' Thus eternal life has its beginning here in this life; and it is here that we sow the seeds of eternal torment.
As a man cannot remain unscathed who spares his enemy on the field of battle, so a man engaged in spiritual warfare cannot save his soul if he spares his body.
What does it mean to be as wise as a serpent? When a serpent is attacked, it is willing to have much of its body severed, as long as it saves the head. So to be wise as a serpent means to be willing to lose everything - your wealth, your reputation, your friends - as long as you save your faith. Your faith is your head, by which you learn all truth; and by that truth your soul is set free. We should, however, recognize that the wisdom of the serpent is not enough; we must be honest and innocent as doves. Indeed it is the combination of wisdom and innocence that creates virtue. The person who is wise as a serpent can sustain the most terrible attacks and still continue to flourish as a disciple of Christ. The person who is innocent refuses to retaliate against those who make the attacks. To be as innocent as a dove means never to take revenge on those who wrong you or undermine you. Unless wisdom is tempered by innocence, one attack provokes another, and conflict continues without end. Unless innocence is tempered by wisdom, a person is so vulnerable that he will not even survive a single attack. Rest assured that no one can ever take away your faith; your wisdom guards against that. But be careful never to bear a grudge against anyone who does you wrong.
In preparing for battle, however, do not think that you will always be victorious. Often there will be only hardship that will bring nothing but affliction... Provide yourself with only one thing, strong courage: no matter what happens, stay with what you have begun... No matter how life goes, whatever successes and failures there are, you should give all of this over to God's will.
Having guarded ourselves against distractions and worries, let us turn our attention to our body on which mental vigilance is completely dependent. Human bodies differ widely from one another in strength and health. Some by their strength are like copper and iron; others are frail like grass. For this reason everyone should rule his body with great prudence, after exploring his physical powers. For a strong and healthy body, special fasts and vigils are suitable; they make it lighter, and give the mind a special wakefulness. A weak body should be strengthened by food and sleep according to one's physical needs, but on no account to satiety. Satiety is extremely harmful even for a weak body; it weakens it, and makes it susceptible to disease. Wise temperance of the stomach is a door to all the virtues. Restrain the stomach, and you will enter Paradise. But if you please and pamper your stomach, you will hurl yourself over the precipice of bodily impurity, into the fire of wrath and fury, you will coarsen and darken your mind, and in this way you will ruin your powers of attention and self-control, your sobriety and vigilance…
Courage does not consist in defeating and oppressing one's neighbor, for this is overbearingness, which oversteps the bounds of courage. Nor again does it consist in fleeing terrified from the trials that come as a result of practicing the virtues; for this is cowardice and falls short of courage. Courage itself consists in persisting in every good work and in overcoming the passions of soul and body. For our struggle is not against flesh and blood, that is, against men, as was the case with the Jews of old, where to conquer other nations was to do the work of God; it is against principalities and powers, that is, against the unseen demons (Ephesians 6:12). He who is victorious conquers spiritually; otherwise he is conquered by the passions. The warfare described in the Old Testament prefigures our spiritual warfare. These two passions of overbearingness and cowardice, though they appear to be opposites, are both caused by weakness. Overbearingness pulls one upwards and is outwardly something startling and frightening, like some powerless bear, while cowardice flees like a chased dog. No one who suffers from either of these two passions puts his trust in the Lord, and therefore he cannot stand firm in battle, whether he is overbearing or cowardly. But the righteous man is as bold as a lion (Proverbs 28:1) in Christ Jesus our Lord, to whom be glory and dominion throughout the ages.
To be a righteous man among the righteous is a great and praiseworthy thing. But it is a far greater and more praiseworthy thing to be a righteous man among the unrighteous.
When the flesh flourishes, the soul fades; when the flesh has full liberty, the soul is straitened; when the flesh is satiated, the soul hungers; when the flesh is adorned, the soul is deformed; when the flesh overflows with laughter, the soul is surrounded by misfortune; when the flesh is in the light, the soul is in darkness...