For, unless He purposed to give them an inheritance after correction, He would not have a care to educate them by afflictions.
For hence the Lord says to John by the angel, Whom I love I rebuke and chasten (Rev. 3:19; Prov. 3:11).
Hence again it is written, My son despise not thou the discipline of the Lord, nor faint when thou art rebuked of Him. For whom the Lord loveth He chasteneth, and scourgeth every son whom He receiveth (Heb. 12:5, 6).
Hence the Psalmist says, Many are the tribulations of the righteous, and out of all these hath the Lord delivered them (Ps. 32:20).
[…] The sick are to be told that, if they believe the heavenly country to be their own, they must needs endure labours in this as in a strange land.
For hence it was that the stones were hammered outside, that they might be laid without sound of hammer in the building of the temple of the Lord.
Bbecause, that is, we are now hammered with scourges without, that we may be afterwards set in our places within, without stroke of discipline, in the temple of God; to the end that strokes may now cut away whatever is superfluous in us, and then the concord of charity alone bind us together in the building.
The sick are to be admonished to consider what severe scourges of discipline chastise our sons after the flesh for attaining earthly inheritances.
What pain, then, of divine correction is hard upon us, by which both a never-to-be-lost inheritance is attained, and punishments which shall endure for ever are avoided?
For hence Paul says, We have had fathers of our flesh as our educators, and we gave them reverence: shall we not much more be in subjection unto the Father of spirits and live? And they indeed for a few days educated us after their own will; but He for our profit in the receiving of His sanctification (Heb. 12:9, 10).
The sick are to be admonished to consider how great health of the heart is in bodily affliction, which recalls the mind to knowledge of itself, and renews the memory of infirmity which health for the most part casts away, so that the spirit, which is carried out of itself into elation, may be reminded by the smitten flesh from which it suffers to what condition it is subject.
Gregory the Great (c.540-604): Pastoral Rule, 3, 12.