And yet in that body we have more than 200 bones, of complex and varied forms, any irregularity in, or injury to, which would of course grievously interfere with our movements. We have over 500 muscles; each nourished by almost innumerable blood vessels, and regulated by nerves. One of our muscles, the heart, beats over 30,000,000 times in a year, and if it once stops, all is over. In the skin are wonderfully varied and complex organs--for instance, over 2,000,000 perspiration glands, which regulate the temperature and communicate with the surface by ducts, which have a total length of some ten miles. Think of the miles of arteries and veins, of capillaries and nerves; of the blood, with the millions of millions of blood corpuscles, each a microcosm in itself. Think of the organs of sense,--the eye with its cornea and lens, vitreous humor, aqueous humor, and choroid, culminating in the retina, no thicker than a sheet of paper, and yet consisting of nine distinct layers, the innermost composed of rods and cones, supposed to be the immediate recipients of the undulations of light, and so numerous that in each eye the cones are estimated at over 3,000,000, the rods at over 30,000,000. Above all, and most wonderful of all, the brain itself. Meinert has calculated that the gray matter of the convolutions alone contains no less than 600,000,000 cells; each cell consists of several thousand visible atoms, and each atom again of many millions of molecules. And yet with reasonable care we can most of us keep this wonderful organization in health; so that it will work without causing us pain, or even discomfort, for many years; and we may hope that even when old age comes "Time may lay his hand Upon your heart gently, not smiting it But as a harper lays his open palm Upon his harp, to deaden its vibrations." [1] Herrick. [2] Hamerton. [3] Hazlitt. [4] Francis. [5] Hazlitt. [6] Trench. [7] Gray. CHAPTER IV. LOVE. "Love rules the court, the camp, the grove, And men below and saints above; For love is heaven and heaven is love." SCOTT. CHAPTER IV. LOVE. Love is the light and sunshine of life. We are so constituted that we cannot fully enjoy ourselves, or anything else, unless some one we love enjoys it with us. Even if we are alone, we store up our enjoyment in hope of sharing it hereafter with those we love. Love lasts through life, and adapts itself to every age and circumstance; in childhood for father and mother, in manhood for wife, in age for children, and throughout for brothers and sisters, relations and friends. The strength of friendship is indeed proverbial, and in some cases, as in that of David and Jonathan, is described as surpassing the love of women. But I need not now refer to it, having spoken already of what we owe to friends. The goodness of Providence to man has been often compared to that of fathers and mothers for their children.