John Calvin Commentary Psalms 78:15

"He clave rocks in the wilderness, And gave them drink abundantly as out of the depths." — Psalms 78:15 (ASV)

He clave the rocks in the wilderness. The Psalmist presents another evidence of God's fatherly love, by which He testified to the greatness of the care He exercised for the welfare of this people. It is not simply said that God gave them drink, but that He did this in a miraculous manner.

Streams, it is true, sometimes issue from rocks, but the rock which Moses struck was completely dry. From this it is evident that the water was not brought forth from any spring, but was made to flow from the greatest depths—as it were, from the very center of the earth.

Therefore, those who have interpreted this passage as meaning that the Israelites drank from bottomless depths because the waters flowed in great abundance have failed to give the true explanation. Moses, in his account of the miracle, further enhances its greatness by indicating that God commanded those waters to gush forth from the most remote veins.

The same truth is confirmed in the following verse, which states that where previously there had not been a single drop of water, there was then a large and mighty river. Had only a small rivulet sprung out of the rock, ungodly men might have had some apparent reason for finding fault with and undervaluing the goodness of God. But when the water gushed out in such copious abundance suddenly, who does not see that the ordinary course of nature was changed, rather than that some vein or spring hidden in the earth was merely opened?