The water in a steam locomotive may be at any one of three temperatures. It may be cold, although clean and ready for the fire. It may be hot, very hot-hot enough to scald you, almost boiling. Or the water may be just one degree hotter-at the boiling point-pouring out its vapor in clouds of steam, pressing through the valves and driving the mighty pistons that turn the wheels and propel the train. There are three kinds of Christians. The first we will call cold-water Christians-perhaps better, clean-water Christians. The second are hot-water Christians. They are almost at the boiling point. One degree more, and we come to the third class of Christians-the boiling-water Christians. The difference between the latter two is a very slight one. It is simply the removal of one last reservation, the dropping of one "if." Yet it makes all the difference in the world. That one degree changes that engine into a motive power, not now just a machine to be looked at, but a locomotive to go.