Hearing these things, let us in our afflictions flee to Him. “And their groaning,” says He, “I have heard:” not simply, “because of their calamities.” But if any should ask, Why then did He suffer them to be evil entreated there? Why, in the first place, to every just man his sufferings are the causes of his rewards. And in the next place, as to why He afflicted them: it was to show His power, that He can (do all), and not only so, but that He may also train them. Observe in fact; when they were in the desert, then they “waxed fat, they grew thick, they spread out in breadth, they kicked”: and ever and always ease was an evil.
Therefore also from the beginning He said to Adam: “In the sweat of your face you shall eat your bread.” Also (it was) in order that having come out of much suffering into rest, they might give thanks to God. For affliction is a great good. For hear the Prophet saying, “It is good for me, that You have humbled me.” But if to great and wonderful men affliction be a great (good), much more to us. And, if you will, let us examine into the nature of affliction as it is in itself.
Let there be some person rejoicing exceedingly, and gay, and giving a loose to jollity: what more unseemly, what more senseless than this? Let there be one sorrowing and dejected: what more truly philosophic than this? For, “It is better,” we read, “to go into the house of mourning, than into the house of laughter.” But, likely enough, you do not like the saying, and want to evade it. Let us however see, what sort of man Adam was in Paradise, and what he was afterwards: what sort of man Cain was before, and what he was afterwards.
The soul does not stand fast in its proper place, but, like as by a running tide, (ῥ εύματος, Edd. πνεύματος, “wind”) is raised and buoyed up by pleasure, having no steadfastness; facile in making professions, prompt at promising; the thoughts all in restless commotion: laughter ill-timed, causeless hilarity, idle clatter of unmeaning talk. And why speak of others? Let us take in hand some one of the saints, and let us see what he was while in pleasure, what again, when in distress.
Shall we look at David himself? When he was in pleasure and rejoicing, from his many trophies, from his victory, from his crowns, from his luxurious living, from his confidence, see what sort of things he said and did: “But I said in my prosperity,” says he, “I shall never be moved.” But when he has come to be in affliction, hear what he says: “And if He say to me, I have no mind for you; lo! Here am I, let Him do that which is pleasing in His sight.” What can be more truly philosophic than these words?
“Whatsoever may be pleasing to God,” says he, “so let it be.” And again he said to Saul: “If the Lord stirs you up against me, may your sacrifice be acceptable.” And then too, being in affliction, he spared even his enemies: but afterwards, not friends even, nor those who had done him no injury. Again, Jacob when he was in affliction, said: “If the Lord will give me bread to eat, and raiment to put on.” As also the son of Noah did nothing of the kind erewhile; but when he was no longer afraid for his safety, you hear how wanton he became. Hezekiah too, when he was in affliction, see what things he did in order to his deliverance; he put on sackcloth, and such like; but when he was in pleasure, he fell through the haughtiness of his heart. For, says the Scripture, “When you have eaten, and drunk, and art filled, take heed to yourself.” For perilous, as on a precipice's brink, is the post of affluence.
“Take heed,” says he, “to yourself.” When the Israelites were afflicted, they became all the more increased in number: but when He left them to themselves, then they all went to ruin. And why speak of examples from the ancients? In our own times, let us see, if you please, is it not the case, that when the most are in good case, they become puffed up, hostile to everybody, passionate, while the power is with them: but if it be taken away, they are gentle, lowly (and as) human beings, are brought to a consciousness of their own natural condition. Therefore the Scripture says, “Pride has holden them unto the end: their iniquity shall go forth as from fatness.”
Source: Homilies on Acts (New Advent)