Water is essential to human life, and has been from the beginning, but it is only a short time ago, relatively speaking, that we learned that water is composed of gas. Two gases got mixed together and could not get apart and we call the mixture water, but it was much more important that man should have had water to drink all these years than it was to find out that water is composed of gas. And there is one thing about water that we do not yet understand, viz., why it differs from other things in this, that other things continue to contract indefinitely under the influence of cold, while water contracts until it reaches a certain temperature and then, the rule being reversed, expands under the influence of more intense cold? It does not make much difference whether we ever learn _why_ this is true, but it is important to the world to know that it is so.
Sometimes I go into a community and find a young man who has come in from the country and obtained a smattering of knowledge; then his head swells and he begins to swagger around and say that an intelligent man like himself cannot afford to have anything to do with anything that he cannot understand. Poor boy, he will be surprised to find out how few things he will be able to deal with if he adopts that rule. I feel like suggesting to him that the next time he goes home to show himself off to his parents on the farm he address himself to the first mystery that ever came under his observation, and has not yet been solved, notwithstanding the wonderful progress made by our agricultural colleges. Let him find out, if he can, why it is that a black cow can eat green grass and then give white milk with yellow butter in it? Will the mystery disturb him? No. He will enjoy the milk and the butter without worrying about the mystery in them.
And so we might take any vegetable or fruit. The blush upon the peach is in striking contrast to the serried walls of the seed within; who will explain the mystery of the apple, the queen of the orchard, or the nut with its meat, its shell, and its outer covering? Who taught the tomato vine to fling its flaming many-mansioned fruit before the gaze of the passer-by, while the potato modestly conceals its priceless gifts within the bosom of the earth?