James presses the same point from a second angle. A spring gives one kind of water; a tree bears one kind of fruit. Gill puts it simply: "a fig tree produces figs, and an olive tree olive berries." Barnes says it is "impossible in nature, and equally absurd in morals." Gill states the aim: "The design of these similes is to observe how absurd a thing it is that a man should both bless and curse with his tongue." The first question asks about the fig tree; the second asks the same about the vine. Both expect a firm no.

James answers in the same verse: "so can no fountain both yield salt water and fresh" (James 3:12). Each source gives what belongs to it. He then asks, "Who is a wise man and endued with knowledge among you?" and calls for a life that shows "meekness of wisdom" (James 3:13).

James draws on three familiar plants: the fig tree, the olive, and the vine. Barnes ties the whole passage back to James 3:1, "be not many masters" (teachers). He says these pictures serve "the main purpose which he had in view, to repress the desire of becoming public teachers without suitable qualifications." The last clause reads differently in the KJV and the ESV because the Greek texts differ. The Textus Receptus behind the KJV includes the word pege, fountain ("so can no fountain"), while the text behind the ESV does not ("Neither can a salt pond").

The question rests on the way God made living things, each yielding fruit "after his kind" (Genesis 1:11-12). James uses that order to show what speech reveals. Matthew Henry's Concise Commentary says, "Pious and edifying language is the genuine produce of a sanctified heart," and that no one should expect cursing from a true believer, "any more than they look for the fruit of one tree from another."

Jesus taught the same: "by their fruits ye shall know them" (Matthew 7:20), and "out of the abundance of the heart the mouth speaketh" (Matthew 12:34). The fruit of the tongue shows the root. James' hope is not better self-control alone, but a heart changed by the wisdom from above that is "full of mercy and good fruits" (James 3:17).