The understanding referred to here is not natural understanding but spiritual, and a man who is regarded as simple by the great ones of this world can have more spiritual understanding than many who look down on him from a lofty height. Just as the first half of the verse speaks about profitable words, so the second half speaks of foolish words, even though only the outcome of those words is referred to – a rod for the back of the speaker. The two things that are contrasted seem to be very different, but they are contrasted because they are both outcomes of speech. Each one by his speech creates a window on his soul offering a view into his character. Those who value wisdom find it on the lips of the man of understanding. They come to converse, to learn, to seek advice, and they find something which the world cannot afford; he knows how to speak skilfully in every situation. He does not speak in such a way as to antagonise everybody, particularly unbelievers, but has the ability to calm people, the ability to advise and to encourage others in difficult circumstances, to befriend others. It requires much grace to reprove others sometimes, and to keep others on the straight and narrow; he has the ability to say no to certain things, even enticing things, when there is flattery from the world, or even from fellow Christians. He knows how to witness, of course, to the Lord, and to withhold words at times and to say little or nothing. But the man who is void of understanding – the one who does not believe in God – impresses the wise only with his ignorance. He may say much or little, but his words miss the mark, fail to help, impart confusion, stir up strife and hatred, and swell with vain boasts. Sooner or later, says Gill, he is chastised for it, so that it can be said a rod has already been prepared for his back. Like an unruly beast of burden he needs constant correction and redirection.