There is scarcely any one who is ashamed to acknowledge that every thing good which he possesses comes from God; but, after making this acknowledgment, they imagine that universal grace has been given to them, as if it had been implanted in them by nature. But Christ dwells principally on this, that the vital sap ”” that is, all life and strength ”” proceeds from himself alone. Hence it follows, that the nature of man is unfruitful and destitute of everything good; because no man has the nature of a vine, till he be implanted in him. But this is given to the elect alone by special grace. So then, the Father is the first Author of all blessings, who plants us with his hand; but the commencement of life is in Christ, since we begin to take root in him. When he calls himself the true vine the meaning is, I am truly the vine, and therefore men toil to no purpose in seeking strength anywhere else, for from none will useful fruit proceed but from the branches which shall be produced by me.
–Commentary on John, Volume II