The sin of our fallen nature is a very mysterious thing. We read of the mystery of iniquity as well as of the mystery of godliness; and the former has lengths, depths, and breadths as well as the latter; depths which no human plumbline ever fathomed, and lengths which no mortal measuring line ever yet meted out. Thus the way in which sin sometimes seems to sleep, and at other times to awake up with renewed strength, its active, irritable, impatient, restless nature, the many shapes and colours it wears, the filthy holes and puddles in which it grovels, the corners into which it creeps, its deceitfulness, hypocrisy, craft, plausibility, intense selfishness, utter recklessness, desperate madness, and insatiable greediness are secrets, painful secrets, only learnt by bitter experience.
In the spiritual knowledge of these two mysteries, the mystery of sin and the mystery of salvation, all true religion consists. In the school of experience we are kept, day after day, learning and forgetting these two lessons, being never able to understand them, and yet not satisfied unless we know them, pursuing after an acquaintance with them, and finding that they still, like a rainbow, recede from us as fast as we pursue. Thus we find realised in our own souls those heavenly contradictions, those divine paradoxes, that the wiser we get, the greater fools we become (1 Cor. 3:18); the stronger we grow, the weaker we are (2 Cor. 12:9, 10); the more we possess, the less we have (2 Cor. 6:10); the more completely bankrupt, the more frankly forgiven (Luke 7:42); the more utterly lost, the more perfectly saved; and when most like a little child, the greatest in the kingdom of heaven (Matt. 18:4).