John Calvin Commentary Psalms 33:17

"A horse is a vain thing for safety; Neither doth he deliver any by his great power." — Psalms 33:17 (ASV)

A horse is a deceitful thing for safety. In this verse, the Psalmist, using the figure of synecdoche, explains that the term horse is to be understood to mean any kind of help.

The meaning is that, generally, those who think their lives are well protected by earthly means are often disappointed at the critical moment of danger. They are miserably deceived to their complete ruin, so that God, in this, clearly shows them their folly.

It is true that kings are not armed with the sword in vain, nor is the use of horses superfluous. Neither are the treasures and resources that God provides to defend human lives unnecessary, provided they are used correctly.

However, because most people, the more they are surrounded by human defences, withdraw farther from God, and by a false imagination persuade themselves that they are in a haven, safe from all disturbance, God acts with perfect justice in thwarting this madness.

This is why his gifts often prove ineffective: because the world, by separating them from the giver, is also justly deprived of his blessing.