What shall we say then? (St. Paul's usual phrase, with μὴ γένοιτο following, for meeting and rejecting a possible misunderstanding of his meaning; cf. Romans 6:1.) Is the Law sin? God forbid. Nay, I had not known Bin, but through law.
αλλὰ, translated "nay," being thus taken, as in the Authorized Version, adversatively to the supposition of the Law being sin, and so a continuation of what is expressed by μὴ γένοιτο. So far from the Law being sin, it exposes sin.
Or it may be in the sense of "howbeit," as in the Revised Version, meaning—still, law has to do with sin so far as this, that it brings it out. For I had not known lust, except the Law had said, Thou shalt not covet; or rather, thou shalt not lust, so as to retain the correspondence of the verb with the preceding substantive.
Observe, here as elsewhere, the significance of νόμος with and without the article. In the preceding section it was the Mosaic Law that wad specially in view, and it is the idea of being sin that is so indignantly repudiated at the beginning of this verse.
So also, at the end, the Law of Moses is referred to as forbidding lust. Hence the article in both cases. But in the intervening phrase, εἰ μὰ διὰ νόμον, it is the principle of law generally that is regarding as making sin known.
The adducing of ἐπιθυμία as being made known by the Law seems to have a significance beyond that of its being one particular instance of sin being so made known. It may imply that the very propension to evil, which is the root of sin, is thus only made known as sinful.
The reference is, of course, to the tenth commandment. Without it men might not have been aware of the sinfulness of desires as well as of deeds, and thus, after all, been unacquainted with the essence of sin.
Further, we may suppose it to be not without a purpose that the apostle varies his verbs expressive of knowing, τὴν ἁμαρτίαν οὐκ ἔγνων, and ἀπιθυμίαν οὐκ ἤδειν ἔγνων. majus est, ἤδειν minus.
Hinc posterius, cure etiam minor gradus negatur, est in increments" (Bengel). ἔγνων may express personal acquaintance with the working and power of sin; ἤδειν, no more than knowing lust as being sin at all.
If so, it does not in itself imply that the Law excites lust, in the sense that I should not have lusted as I do had not the Law forbidden me to lust.