In reflecting on what these great men accomplished, it is interesting to point out to ourselves that the consensus of opinion seems to be that, for most people, "the pursuit of happiness" is the main business of life. Whether this ought to be or not, should not distract our attention from the fact that it really is. To most of us--at least to those of us who are young--happiness seems to lie in the thing pursued, provided the pursuit succeeds. We all seek the crock of gold at the end of the rainbow, and imagine that if we get it, we shall get the _summum bonum_ of everything--happiness. Yet all one has to do is to remember how happy he was one day when he was feeling well physically, morally, mentally and spiritually (as we all have at rare intervals), to realize that happiness is merely a condition,--and that it is a condition that depends more on _the condition of his own machine than on all other things put together_. When one observes the action of a fine trotting horse, the smooth and noiseless motion of a large steam-engine, or the majestic setting of the sun; or when he hears the harmonies of some great musical composer, or the grander harmonies of the ocean-breakers on the beach; or when he ponders on the inconceivably swift but God-like regularity of the stars and planets, he may get a faint and brief conception of what it means for a machine to be in order. Our human machines are rarely in this condition: but sometimes, without any assignable cause whatever, one takes a deep, full breath, and says, "It is good to live." The men just spoken of, and the great teachers of truth in all ages, in even a higher degree, admonish us to keep our machines in order, and tell us how to do it. How not to do it, the world and the flesh and the devil tell us unceasingly; beguiling us, as the serpent beguiled Eve, to eat; to gratify one and all the appetites of the senses, regardless of the effect on the machine inside. For we know those senses ought to guard our intake valves, but do not.