Wherefore, Ambrose appears to me to have most elegantly adverted to the blessing of Jacob as an illustration of this righteousness, when he says that as he who did not merit the birthright in himself personated his brother, put on his garments which gave forth a most pleasant odour, and thus introduced himself to his father that he might receive a blessing to his own advantage, though under the person of another, so we conceal ourselves under the precious purity of Christ, our first-born brother, that we may obtain an attestation of righteousness from the presence of God. The words of Ambrose are,—“Isaac’s smelling the odour of his garments, perhaps means that we are justified not by works, but by faith, since carnal infirmity is an impediment to works, but errors of conduct are covered by the brightness of faith, which merits the pardon of faults,” (Ambrose de Jacobo et Vita Beats, Lib. 2, c. 2). And so indeed it is; for in order to appear in the presence of God for salvation, we must send forth that fragrant odour, having our vices covered and buried by his perfection.
-Calvin's Institutes 3.11.23
