'Olive tree' in the Bible

And if certain of the branches were broken off, and thou, being a wild olive tree, wast graffed in among them, and a fellow-partaker of the root and of the fatness of the olive tree didst become --

for if thou, out of the olive tree, wild by nature, wast cut out, and, contrary to nature, wast graffed into a good olive tree, how much rather shall they, who are according to nature, be graffed into their own olive tree?