Charles H. Spurgeon on Psalms 19:12

"Secret faults." Sins may be termed "secret" either, 1. When they are coloured and disguised —though they do fly abroad, yet not under that name, but apparelled with some semblance of virtues. Cyprian complains of such tricks in his second epistle, which is to Donatus. 2. When they are kept off from the stage of the world; they are like fire in the chimney; though you do not see it, yet it burns. So many a person, like those in Ezekiel, "commit abominations in secret" —that is, so as the public eye is not upon them. He is sinful, and acts it with the greatest vileness; all the difference betwixt another sinner and him is this —that he is, and the other saith he is, a sinner. Just as 'twixt a book shut and a book opened; that which is shut hath the same lines and words, but the other being opened every man may see and read them. 3. When they are kept, not only from the public eye, but from any mortal eye; that is, the carnal eye of him who commits the sins sees them not; he doth, indeed, see them with the eye of conscience, but not with the eye of natural sense. Even those persons with whom he doth have converse, and who highly commend the frame of his ways, cannot yet see the secret discoursings and actings of sin in his mind and heart. For, brethren, all the actings of sin are not without, they are not visible; but there are some, yes, the most dangerous actings within the soul, where corruption lies as a fountain and root. The heart of man is a scheme of wickedness; nay, a man saith that in his heart which he dares not speak with his tongue, and his thought will do that which his hands dare not to execute. Well, then, sin may be called "secret" when it is sin, and acted as sin, even there, where none but God and conscience can see. Methinks sin is like a candle in a lantern, where the shining is first within and then bursting out at the windows; or like evils and ulcerous humours, which are scabs and scurvy stuff, first within the skin, and afterwards they break out to the view on the outside. So it is with sin; it is a malignant humour and a fretting leprosy, diffusing itself into several secret acts and workings within the mind, and then it breaks abroad and dares adventure the practice of itself to the eye of the world; and be it that it may never see the light, that it may be like a child born and buried in the womb, yet as that child is a man, a true man there closeted in that hidden frame of nature, so sin is truly sin, though it never gets out beyond the womb which did conceive and enliven it. —Obadiah Sedgwick.