John Gill's Exposition of the Whole Bible
Proverbs 21:1
The king's heart [is] in the hand of the Lord, [as] the rivers of water,.... The heart of every king, and all that is in it, his thoughts, counsels, purposes, and designs; the hearts of bad kings, as Pharaoh, whom the Lord hardened and softened at pleasure; the antichristian kings, into whose hearts he put it to give their kingdoms to the beast, Revelation 17:17; the hearts of good kings, as David, Solomon, Cyrus, and others: and if the hearts of kings are in the hands of the Lord, which are full of things of the greatest importance with respect to the government of the world; and which are generally more untractable and unmanageable; and who are more resolute and positive, and will have their own wills and ways, especially arbitrary princes; then much more the hearts of other persons. And which are as "rivers of water"; for so the words may be rendered, as rivers of water is "the heart of a king", which is "in the hand of the Lord"; unstable, fluid, and fluctuating; and yet the Lord can stay and settle, and fix them, and keep them steady and within bounds: or which, like a torrent of water, comes with force and impetus; and so the Septuagint render it, "the force of waters"; and bears all before it, as do the wills of despotic kings; and yet these the Lord can stop and bound, and rule and overrule: or like rivers of water, reviving and refreshing, so is the heart of a good king, full of wisdom and prudence, of integrity and faithfulness, of clemency and goodness; the streams of whose bounty and kindness flow among his subjects, to their great pleasure and profit; so Christ, the King of kings, is said to be as "rivers of water",
Isaiah 32:2. The allusion is to gardeners, that make channels for the water to run in, to water their gardens; or to husbandmen, that cut aqueducts from rivers, to water their fields; or to the turning of the course of rivers, as Euphrates was by Cyrus, when he took Babylon. The heart of a king is as much at the dispose of the Lord, and can be turned by him as easily as such canals may be made, or the course of a river turned; for it follows:
he turneth it whithersoever he will; contrary to their first designs, and to answer another purpose; oftentimes towards his people, and for the good of his cause and interest, which they never designed; and to bring about such things as were out of their view. And so, in conversion, the Lord can turn the hearts of men as he pleases; their understanding, will, and affections, are in his hands: he can make the understanding light which was darkness, and so turn it from darkness to light; he can take off the stiffness of the will, and turn it from its bias and bent, and make it willing to that which is good in the day of his power: he can turn the channel and course of the affections from sinful lusts and pleasures, to himself, his son, his truths, word, worship, ordinances, and people; he can take out of the heart what he pleases, its ignorance, hardness, enmity, unbelief, pride, and vanity; and he can put in what he pleases, his fear, his laws, his Spirit, and the gifts and graces of if; he can change and turn it just as he will; he that made the heart can operate upon it, and do with it as seems good in his sight. The Heathens very wrongly call one of their deities Verticordia o, from the power of turning the heart they ascribe to it; however, this shows their sense, that to turn the heart is the property of deity.
o Valer. Maximus, l. 8. c. 15. s. 12. Vid. Ovid. Fasti, l. 4. v. 158.