Albert Barnes Commentary Romans 11:17

"But if some of the branches were broken off, and thou, being a wild olive, wast grafted in among them, and didst become partaker with them of the root of the fatness of the olive tree;" — Romans 11:17 (ASV)

If some of the branches. The illustration here is taken from the practice of those who graft trees. The useless branches, or those which bear poor fruit, are cut off, and a better kind inserted. "If some of the natural descendants of Abraham, the holy root, are cast off because they are unfruitful, that is, because of unbelief and sin."

And thou. The word thou here is used to denote the Gentile, whom Paul was then particularly addressing.

Being a wild olive tree. From this passage, it would seem that the olive tree was sometimes cultivated, and that cultivation was necessary in order to render it fruitful. The cultivated olive tree is "of a moderate height, its trunk knotty, its bark smooth
and ash-coloured, its wood is solid and yellowish, the
leaves are oblong, and almost like those of the willow,
of a green colour, etc. The wild olive is smaller in all
its parts" (Calmet).

The wild olive was unfruitful, or its fruit very imperfect and useless. The ancient writers explain this word by "unfruitful, barren" (Schleusner). This was used, therefore, as the emblem of unfruitfulness and barrenness, while the cultivated olive produced much fruit. The meaning here is that the Gentiles had been like the wild olive, unfruitful in holiness; they had been uncultivated by the institutions of the true religion and, consequently, had grown up in the wildness and sin of nature. The Jews had been like a cultivated olive, long under the training and blessing of God.

Wert grafted in. The process of grafting consists in inserting a scion or a young shoot into another tree. To do this, a useless limb is removed, and the grafted limb produces fruit according to its new nature or kind, and not according to the tree in which it is inserted. In this way, a tree that bears no fruit, or whose branches are decaying, may be recovered and become valuable.

The apostle's figure is a very vivid and beautiful one. The ancient root or stock, that of Abraham, etc., was good. The branches—the Jews in the time of the apostle—had become decayed and unfruitful, and broken off. The Gentiles had been grafted into this stock and had restored the decayed vigor of the ancient people of God; and a fruitless church had become vigorous and flourishing. But the apostle soon proceeds to keep the Gentiles from exaltation on account of this.

Among them. Among the branches, so as to partake with them of the juices of the root.

Partakest of the root. The grafted limb would derive nourishment from the root as much as though it were a natural branch of the tree. The Gentiles derived now the benefit of Abraham's faith and holy labors, and of the promises made to him and to his seed.

Fatness of the olive tree. The word fatness here means fertility, fruitfulness—the rich juices of the olive producing fruit. See Judges 9:9.