There are three very grievous kinds of war.
The one is public, when our soldiers are attacked by foreign armies.
The second is, when even in time of peace, we are at war with one another.
The third is, when the individual is at war with himself, which is the worst of all.
For foreign war will not be able to hurt us greatly. What, I pray, though it slaughters and cuts us off? It injures not the soul. Neither will the second have power to harm us against our will; for though others be at war with us, we may be peaceable ourselves. For so says the Prophet, ‘For my love they are my adversaries, but I give myself unto prayer’ (Ps. 109:4); and again, ‘I was at peace with them that hate peace’; and, ‘I am for peace; but when I speak, they are for war.’ (Ps. 120:6, 7, LXX)
But from the third, we cannot escape without danger. For when the body is at variance with the soul, and raises up evil desires, and arms against it sensual pleasures, or the bad passions of anger, and envy; we cannot attain the promised blessings, till this war is brought to an end; whoever does not still this tumult, must fall pierced by wounds that will bring that death that is in hell. We have daily need therefore of care and great anxiety, that this war may not be stirred up within us, or that, if stirred up, it may not last, but be quelled and laid asleep.
– St John Chrysostom