Paul is generalising his own experience when he speaks of the condemnation of an intrusive alien force that holds unregenerate human nature in bondage. He is writing a page of his own autobiography, and he is sure that all the rest of us have like pages in ours. Heart answereth unto heart as in a mirror. If each man is a unity, the poison must run through all his veins and affect his whole nature. Will, understanding, heart, must all be affected and each in its own way by the intruder; and if men are a collective whole, each man's experience is repeated in his brother's.
The Apostle is equally transcribing his own experience when in the text he sadly admits the futility of all efforts to shake the dominion of sin. He has found in his own case that even the loftiest revelation in the Mosaic law utterly fails in the attempt to condemn sin. This is true not only in regard to the Mosaic law but in regard to the law of conscience, and to moral teachings of any kind. It is obvious that all such laws do condemn sin in the sense that they solemnly declare God's judgment about it, and His sentence on it; but in the sense of real condemnation, or casting out, and depriving sin of its power, they all are impotent. The law may deter from overt acts or lead to isolated acts of obedience; it may stir up antagonism to sin's tyranny, but after that it has no more that it can do. It cannot give the purity which it proclaims to be necessary, nor create the obedience which it enjoins. Its thunders roll terrors, and no fruitful rain follows them to soften the barren soil. There always remains an unbridged gulf between the man and the law.
And this is what Paul points to in saying that it was weak through the flesh.' It is good in itself, but it has to work through the sinful nature. The only powers to which it can appeal are those which are already in rebellion. A discrowned king whose only forces to conquer his rebellious subjects are the rebels themselves, is not likely to regain his crown. Because law brings no new element into our humanity, its appeal to our humanity has little more effect than that of the wind whistling through an archway. It appeals to conscience and reason by a plain declaration of what is right; to will and understanding by an exhibition of authority; to fears and prudence by plainly setting forth consequences. But what is to be done with men who know what is right but have no wish to do it, who believe that they ought but will not, who know the consequences but choose rather the pleasures of sin for a season,' and shuffle the future out of their minds altogether? This is the essential weakness of all law. The tyrant is not afraid so long as there is no one threatening his reign, but the unarmed herald of a discrowned king. His citadel will not surrender to the blast of the trumpet blown from Sinai.
