Psalms 96:12

When the Lord invites certain ones from villages and streets to the supper, He clearly designates that people who had known how to keep the law under civilized society; but when He commands His guests to be gathered from highways and hedges, He doubtless seeks to gather a rustic people, that is, the Gentiles, of whose signification it is said through the Psalmist: "Then shall all the trees of the forest rejoice before the face of the Lord, because He comes." For the trees of the forest are called the Gentiles, because in their unbelief they were always twisted and unfruitful. Those therefore who were converted from that rustic way of life came to the Lord's supper as if from hedges.

"The plains shall be joyful, and all things that are in them" [Psalm 96:12]. All the meek, all the gentle, all the righteous, are the "plains" of God. "Then shall all the trees of the woods rejoice." The trees of the woods are the heathen. Why do they rejoice? Because they were cut off from the wild olive, and engraffed into the good olive. [Romans 11:17] "Then shall all the trees of the woods rejoice:" because huge cedars and cypresses have been cut down, and undecaying timbers have been bought for the building of the house. They were trees of the woods; but before they were sent to the building: they were trees of the woods, but before they produced the olive.