Pope St. Leo, who reigned from 440 to 461, explains the effects that Christ’s Resurrection has on our souls. A particularly fitting meditation for Eastertide:
“The first man is of the earth earthy,” says the Apostle, “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.” (I Cor. 15:47-49)
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.
And hence that the disturbed minds of the disciples might not be racked by prolonged grief, He with such wondrous speed shortened the three days' delay which He had announced, that by joining the last part of the first and the first part of the third day to the whole of the second, He cut off a considerable portion of the period, and yet did not lessen the number of days.
The Savior's Resurrection therefore did not long keep His soul in Hades, nor His flesh in the tomb; and so speedy was the quickening of His uncorrupted flesh that it bore a closer resemblance to slumber than to death, seeing that the Godhead, Which quitted not either part of the Human Nature which He had assumed, reunited by Its power that which Its power had separated.
Let God's people then recognize that they are a new creation in Christ, and with all vigilance understand by Whom they have been adopted and Whom they have adopted. Let not the things, which have been made new, return to their ancient instability; and let not him who has put his hand to the plough (Lk. 9:62) forsake his work, but rather attend to that which he sows than look back to that which he has left behind. (Ph. 3:14)
Let no one fall back into that from which he has risen, but, even though from bodily weakness he still languishes under certain maladies, let him urgently desire to be healed and raised up. For this is the path of health through imitation of the Resurrection begun in Christ.
St. Leo the Great, Sermon on the Resurrection (Sermon 71)