'Harmless' is more correctly pure, all of a piece, homogeneous and entire. It expresses what the Christian life should be in itself, whilst the former designation describes it more as it appears. The piece of cloth is to be so evenly and carefully woven that if held up against the light it will show no flaws nor knots. Many a professing Christian life has a veneer of godliness nailed thinly over a solid bulk of selfishness. There are many goods in the market finely dressed so as to hide that the warp is cotton and only the weft silk. No Christian man who has memory and self-knowledge can for a moment claim to have reached the height of his ideal; the best of us, at the best, are like Nebuchadnezzar's image, whose feet were iron and clay, but we ought to strain after it and to remember that a stain shows most on the whitest robe. What made David's sin glaring and memorable was its contradiction of his habitual nobler self. One spot more matters little on a robe already covered with many. The world is fully warranted in pointing gleefully or contemptuously at Christians' inconsistencies, and we have no right to find fault with their most pointed sarcasms, or their severest judgments. It is those 'that bear the vessels of the Lord' whose burden imposes on them the duty 'be ye clean,' and makes any uncleanness more foul in them than in any other. The Apostle sets forth the place and function of Christians in the world, by bringing together in the sharpest contrast the 'children of God' and a 'crooked and perverse generation.' He is thinking of the old description in Deuteronomy, where the ancient Israel is charged with forgetting 'Thy Father that hath bought thee,' and as showing by their corruption that they are a 'perverse and crooked generation.' The ancient Israel had been the Son of God, and yet had corrupted itself; the Christian Israel are 'sons of God' set among a world all deformed, twisted, perverted. 'Perverse' is a stronger word than 'crooked,' which latter may be a metaphor for moral obliquity, like our own right and wrong, or perhaps points to personal deformity. Be that as it may, the position which the Apostle takes is plain enough. He regards the two classes as broadly separated in antagonism in the very roots of their being. Because the 'sons of God' are set in the midst of that 'crooked and perverse generation' constant watchfulness is needed lest they should conform, constant resort to their Father lest they should lose the sense of sonship, and constant effort that they may witness of Him. III. The solemn reason for this aim.