In my last sermon…we explained to you our participation in the cross of Christ, whereby the life of believers contains in itself the mystery of Easter, and thus what is honoured at the feast is celebrated by our practice.
And how useful this is you yourselves have proved, and by your devotion have learned, how greatly benefited souls and bodies are by longer fasts, more frequent prayers, and more liberal alms.
For there can be hardly anyone who has not profited by this exercise, and who has not stored up in the recesses of his conscience something over which he may rightly rejoice.
[…] Since, therefore, by our forty days’ observance we have wished to bring about this effect, that we should feel something of the Cross at the time of the Lord’s Passion, we must strive to be found partakers also of Christ’s Resurrection, and pass from death unto life (1 John 3:14), while we are in this body.
For when a man is changed by some process from one thing into another, not to be what he was is to him an ending, and to be what he was not is a beginning.
But the question is, to what a man either dies or lives: because there is a death, which is the cause of living, and there is a life, which is the cause of dying.
And nowhere else but in this transitory world are both sought after, so that upon the character of our temporal actions depend the differences of the eternal retributions.
We must die, therefore, to the devil and live to God: we must perish to iniquity that we may rise to righteousness.
Let the old sink, that the new may rise; and since, as says the Truth, no one can serve two masters (Matthew 6:24), let not him be Lord who has caused the overthrow of those that stood, but Him Who has raised the fallen to victory.
Accordingly, since the Apostle says, the first man is of the earth earthy, the second man is from heaven heavenly. As is the earthy, such also are they that are earthy; and as is the heavenly, such also are they that are heavenly.
As we have borne the image of the earthy, so let us also bear the image of Him Who is from heaven , we must greatly rejoice over this change, whereby we are translated from earthly degradation to heavenly dignity through His unspeakable mercy, Who descended into our estate that He might promote us to His, by assuming not only the substance but also the conditions of sinful nature, and by allowing the impassibility of Godhead to be affected by all the miseries which are the lot of mortal manhood.
Leo the Great (c.400-461): Sermon 71, 1-2.