John Calvin Commentary Isaiah 38:13

"I quieted [myself] until morning; as a lion, so he breaketh all my bones: From day even to night wilt thou make an end of me." — Isaiah 38:13 (ASV)

I reckoned till the dawn. Others translate it "I determined," or "I laid down." Here it means what we express by the ordinary phrase, (Je fasoye mon compte,) "I laid my account." From this verse it may be inferred that Hezekiah labored at least two days under the disease, for in the preceding verse he pronounced its severity to be so great that he expected immediate death.

And now, when one day had passed, he still waited till the dawn, and again, from day even to night, so that he said he would die at any moment. The meaning, therefore, is that although he reached "the dawn," he was still hastening to death through constant tossings. This was because, having been struck by a terrible judgment of God, he cared nothing about his life.

As the Greeks, when they intended to say that nothing is more vain than man, said that he was (ἐφήμερον) "an ephemeral animal"—that is, "the creature of a day"—so Hezekiah means by "the life of a day" that which is fading and has no duration.

As a lion, so hath he broken my bones. The comparison of God to a lion should not be considered strange, though God is naturally gracious, merciful, and kind (Exodus 34:6). Nothing certainly can more truly belong to God than these attributes; but we cannot be aware of that gentleness when we have provoked Him by our crimes and urged Him to severity by our wickedness.

Besides, there is no cruelty and fierceness in wild beasts that is fitted to strike such terror as we feel from the mere mention of the name of God, and justly so. For the Lord’s chastisements must have sufficient power to humble us and cast us down to hell itself, so that we will be almost destitute of consolation and regard everything as full of horror.

In like manner, we also see that David described these terrors when he says that his bones are numbered, his couch is moistened with tears, his soul is troubled, and hell is opened (Psalms 6:3–6; Psalms 22:17; Psalms 38:6). Thus, the godly must sometimes be terrified by the judgment of God, so that they may be more powerfully moved to desire His favor.