The Law was committed to writing, in order that it might teach more fully and perfectly that knowledge, both of God and of ourselves, which the law of nature teaches meagrely and obscurely. Proof of this, from an enumeration of the principal parts of the Moral Law; and also from the dictate of natural law, written on the hearts of all, and, in a manner, effaced by sin.
Taken from Calvin’s Institutes 2.8.1,
“I believe it will not be out of place here to introduce the Ten Commandments of the Law, and give a brief exposition of them. In this way it will be made more clear, that the worship which God originally prescribed is still in force (a point to which I have already adverted); and then a second point will be confirmed—viz. that the Jews not only learned from the law wherein true piety consisted, but from feeling their inability to observe it were overawed by the fear of judgments and so drawn, even against their will, towards the Mediator.
In giving a summary of what constitutes the true knowledge of God,192 we showed that we cannot form any just conception of the character of God, without feeling overawed by his majesty, and bound to do him service. In regard to the knowledge of ourselves, we showed that it principally consists in renouncing all idea of our own strength, and divesting ourselves of all confidence in our own righteousness, while, on the other hand, under a full consciousness of our wants, we learn true humility and self-abasement. Both of these the Lord accomplishes by his Law, first, when, in assertion of the right which he has to our obedience, he calls us to reverence his majesty, and prescribes the conduct by which this reverence is manifested; and, secondly, when, by promulgating the rule of his justice (a rule, to the rectitude of which our nature, from being depraved and perverted, is continually opposed, and to the perfection of which our ability, from its infirmity and nervelessness for good, is far from being able to attain), he charges us both with impotence and unrighteousness.
Moreover, the very things contained in the two tables are, in a manner, dictated to us by that internal law, which, as has been already said, is in a manner written and stamped on every heart. For conscience, instead of allowing us to stifle our perceptions, and sleep on without interruption, acts as an inward witness and monitor, reminds us of what we owe to God, points out the distinction between good and evil, and thereby convicts us of departure from duty. But man, being immured in the darkness of error, is scarcely able, by means of that natural law, to form any tolerable idea of the worship which is acceptable to God.
At all events, he is very far from forming any correct knowledge of it. In addition to this, he is so swollen with arrogance and ambition, and so blinded with self-love, that he is unable to survey, and, as it were, descend into himself, that he may so learn to humble and abase himself, and confess his misery. Therefore, as a necessary remedy, both for our dullness and our contumacy, the Lord has given us his written Law, which, by its sure attestations, removes the obscurity of the law of nature, and also, by shaking off our lethargy, makes a more lively and permanent impression on our minds.”