In order that we may be able to overcome all our enemies, let us seek divine aid by the observance of the heavenly bidding, knowing that we cannot otherwise prevail against our adversaries, unless we prevail against our own selves.
For we have many encounters with our own selves: “the flesh desires one thing against the spirit, and the spirit another thing against the flesh” (Gal. 5:17; Rom. 6:12).
And in l.this disagreement, if the desires of the body be stronger, the mind will disgracefully lose its proper dignity, and it will be most disastrous for that to serve which ought to have ruled.
But if the mind, being subject to its Ruler, and delighting in gifts from above, shall have trampled under foot the allurements of earthly pleasure, and shall not have allowed sin to reign in its mortal body, reason will maintain a well-ordered supremacy, and its strongholds no strategy of spiritual wickednesses will cast down: because man has then only true peace and true freedom when the flesh is ruled by the judgment of the mind, and the mind is directed by the will of God.
And although this state of preparedness, dearly-beloved, should always be maintained that our ever-watchful foes may be overcome by unceasing diligence, yet now it must be the more anxiously sought for and the more zealously cultivated when the designs of our subtle foes themselves are conducted with keener craft than ever.
For knowing that the most hallowed days of Lent are now at hand, in the keeping of which all past slothfulnesses are chastised, all negligences alerted for, they direct all the force of their spite on this one thing, that they who intend to celebrate the Lord’s holy Passover may be found unclean in some matter, and that cause of offence may arise where propitiation ought to have been obtained.
Leo the Great (c.400-461): Sermon 39,2.