The Second Lord’s Day

02 The Second Lord’s Day 
Romans 7:7
What shall we say then? Is the law sin? God forbid. Indeed, I would not have known sin except by the law. For I would not have known that concupiscence or lust was a sin unless the law had said, You shall not covet.
The Apostle, that he might stir up the faithful to a new obedience, had proposed to them the difference between the condition of those that are under the Law, and those that are under Grace: that those under the law of the flesh and sin, bring forth fruits unto death; but those who are under the grace of the Spirit, bring forth fruits in a new obedience unto life eternal. But because of this opposition between the Law and Grace, some might gather that there was then a very great agreement between the Law and sin. Therefore in this seventh verse, this objection is anticipated by the Apostle. 1. Then the objection is proposed: What shall we say? Is the Law sin? 2. It is rejected with a certain kind of detestation: God forbid. 3. The case is plainly set down and resolved in these words: I would not have known sin etc. Where the singular effect and use of the Law is declared: that by forbidding and reproving sin, a sense and acknowledgement of sin is begotten in man, as that which is contrary to [the Law]; and therefore [the Law] cannot be the cause of sin.
The Explication. The Law is commonly understood as, a way and rule of walking . Now this way and rule is imposed upon reasonable creatures by divine authority, and by the greatest obligations that can be. And this is the Law of God which the Apostle here understands; especially the moral Law. By sin here is not only understood the transgression of God’s will, but also all those things that follow upon such a transgression, which in Romans 7:1-25 is defined by the name of Death, and is sometimes called misery. Sin is either known confusedly and speculatively only, or more exactly and practically. Now the accurate and practical knowledge of sin is understood here, whereby it is efficaciously concluded in our consciences that sin is a detestable thing, and is to be avoided by all means.
Doctrine 1. Men of their own nature are so blinded that although they are completely drowned in sin and death, yet of themselves they cannot know it.
This is gathered from these words: I would not have known sin.
Reason 1 . Because the very mind and conscience of man, which is his eye and light, is corrupted in a twofold manner. 1. Privitively,1 in that it is deprived of that light whereby it might rightly judge itself, and those things which belong to its spiritual life. 2. Positively, in as much as it is possessed with a certain perverse disposition, from which it often calls evil good, and good evil.2 For as the eye being put out feels nothing, and as the eye infected with diseases, and depraved by the indispositions of the organ, sees all things otherwise than as they are presented, so is it with the eye of the soul. 
Reason 2. Because the whole man is possessed with a certain spiritual disease and, as it were with a drunkenness, and lethargic stupidity, whereby he is sensible of nothing, rightly and spiritually.
1 Privitively: in such a way as to deprive of something. 2 Isaiah 5:20.
Reason 3 . Because we are so borne in sin, that in a way it becomes natural to us, nor have we ever experienced any other condition. Those who are borne with deformed and crooked limbs, never saw a right and well-proportioned disposition of all their members. They do not know that their own limbs are deformed and ill-proportioned, but consider their distortion and disproportion to be the right proportion itself. It is even so in this case of sin, and of the corruption of our nature.
Use 1. Of Admonition: that for this reason we might more and more humble ourselves before God, seeing that we are so miserable, that of ourselves we can never know our own misery. 
Use 2. Of Direction: to deny all our natural wisdom, so that we may fly to God, and seek wisdom from him, so that we may rightly know ourselves and him. 
Doctrine 2. The only way to rightly know sin and the cause of our misery, is by the law of God. It is gathered from these words: For… unless the law had said, etc.
Reason 1. Because the law of God in some way enlightens the eyes of our mind, Psalms 19:1-14. 
Reason 2. Because the law of God is the rule of our life, and is therefore the touchstone not only of the straightness, but also of all the obliquity1 and crookedness of our life. 
Reason 3. Because the law of God is set before us as a mirror in which we may clearly see our faces and quality, James 1:23.2 Now it performs this use of a mirror to us, by a comparison made between the perfection which the Law requires of us, and the manifold defects and deformities that are found in our life.
Questions arising from this. 
Question 1. Did not some wise men, at least among the heathen, know sin without this Law of God?
I answer: 1. They were not altogether without this law of God, because in part they had it written and engraven in their hearts. Yet, 2. They did not know many sins which might easily have been known by the Law. 3. They did not know sin under the first and most proper reason for it; namely, as an offence against God, but only as repugnant to reason in man himself. 4. They did not know those spiritual miseries which accompany sin. 5. They did not know sin practically and efficaciously, so as to be driven by that knowledge to a spiritual humbling of themselves before God.
Question 2. In what manner does this Law of God show us our sin?
I answer: 1. It shows us our duty, or the will of God, that we should do. 2. It shows us our fault in transgressing this will. 3. It shows us our guilt, by which we are bound over to punishment for this guiltiness. 4. It also shows the punishment itself; for the threatenings of the Law, in which the punishments are contained and denounced, are parts of the Law, and belong to its sanctification or ratification.
1 The quality of being deceptive, or slanted. 
2 For if anyone is a hearer of the word and not a doer, he is like a man observing his natural face in a mirror; (James 1:23) 
Use 1. Of Direction: that in passing judgment upon our lives, we do not follow either our own fancies nor the tenets and opinions of the vulgar, but the law of God alone.
Use 2 . Of Admonition: that we often test our life according to that law; and do that for time past, for our greater humiliations, as well as for the time to come, for our caution and better direction in every part of our conversation.1
1 Not speech, but how we deal with others; the way we conduct ourselves; our way of life.