Charles H. Spurgeon on Psalms 47:9

The shields of the earth are God's, is understood by many as spoken of princes. I admit that this metaphor is of frequent occurrence in Scripture, nor does this sense seem to be unsuitable to the scope of the passage...Yet the sense will be more simple if we explain the words thus: That, as it is God alone who defends and preserves the world, the high and supreme majesty which is sufficient for so exalted and difficult a work as the preservation of the world, is justly looked upon with admiration. The sacred writer expressly uses the word shields in the plural number, for, considering the various and almost innumerable dangers which unceasingly threaten every part of the world, the providence of God must necessarily interpose in many ways, and make use, as it were, of many bucklers. John Calvin.