John Calvin Commentary Psalms 38:10

"My heart throbbeth, my strength faileth me: As for the light of mine eyes, it also is gone from me." — Psalms 38:10 (ASV)

My heart has turned round. The verb David uses here signifies to travel or wander here and there; but here it is taken for the agitation or anxiety that distress of heart produces when we do not know what to do. As people are troubled in mind, they turn themselves in all directions, and so their heart may be said to turn round, or to run back and forth.

But since faith, once it has brought us into obedience to God, keeps our minds fixed on his word, it might be asked here, by way of objection, how David's heart was so affected by anxiety and trouble? To this I answer that although he continued to walk in God's ways, while he was sustained by God's promises, he was not entirely exempt from human weakness.

Indeed, it will always happen that as soon as we fall into some danger, our flesh will suggest various schemes and devices to us, and lead us into many errors in our search for counsel; so that even the most confident would fail and go astray, unless he imposed upon himself the same restraint by which David was preserved and kept in subjection, namely, by keeping all his thoughts confined within the limits of God’s word.

Indeed, even in the prayers we offer when our minds are at ease, we know too well how easily our minds are carried away and wander after vain and frivolous thoughts, and how difficult it is to keep them continuously attentive and fixed with the same intensity on the object of our desire.

If this happens when we are not undergoing any severe trial, what will be the case when we are agitated by violent storms and tempests which threaten a thousand deaths, and when there is no way to escape them? It is, therefore, no great wonder if these things carried away David's heart, so that it was subject to various emotions amidst such stormy agitations.

He adds that his strength had failed him, as if he had compared himself to a dead man. What he adds concerning the light of his eyes some understand as if he had said that he was so oppressed with despair on all sides that no counsel or foresight was left to him. The simpler meaning, however, is that the light of life was taken away from him, because the soul's energy principally shows itself in it.