Johannes G. Vos: The Covenant of Works parallels the Covenant of Grace

Johannes G. Vos clearly articulates the importance of the covenant of works as parallel to the way of salvation through Christ (the covenant of grace), which makes sense of the federal (covenantal) headship of Adam and Christ, respectively, in Romans 5 (cf. I Cor. 15:21-22, 45-47):

Why is this doctrine of the covenant of works very important to us as Christians? Because it is parallel to the way of salvation through Jesus Christ. Just as the first Adam brought sin and death, so Christ, the second Adam, brings us righteousness and eternal life. Adam was our representative in the covenant of works; Jesus Christ is our representative in the covenant of grace. Those who reject the doctrine of the covenant of works have no right to claim the blessings of the covenant of grace, for the two are parallel, and stand or fall together, as is proved by Romans 5. (Johannes G. Vos, The Westminster Larger Catechism: A Commentary [Phillipsburg, NJ: Presbyterian and Reformed, 2002], 51-52; quoted by Brian Schwertley in his refutation of the Auburn Avenue theology)