One danger of secret sin is that a man cannot commit it without being by-and-by betrayed into a public sin. If a man commit one sin, it is like the melting of the lower glacier upon the Alps, the others must follow in time. As certainly as you heap one stone upon the cairn to-day, the next day you will cast another, until the heap reared stone by stone shall become a very pyramid. See the coral insect at work, you cannot decree where it shall stay its pile. It will not build its rock as high as you please; it will not stay until an island shall be created. Sin cannot be held in with bit and bridle, it must be mortified.