The folly and wickedness of our practical contempt for the great laws of human growth may be measured by the penalties of suffering, illness, and premature death attached to this neglect. This is rendered more striking by observing, first of all, the great force of the principle of vitality, the strong tendency to live and resist injurious influences, which we all possess. Nothing is more remarkable in the history of the human race than its great power of adaptability. Scattered all over the surface of the globe, under the most varying conditions, men still live and thrive. The cities of Cuença and Quito, at a height of 9,600 feet above the level of the sea, possess large and flourishing populations; so also do the cities of Holland and New Orleans, which lie below its level. Multitudes of workmen live in the galleries of the deepest mines, many hundred feet below the surface of the earth, deprived of light, breathing air much more condensed, living under a much stronger pressure than that of the ordinary atmosphere. And, on the other hand, scientific observers have taken up their residence for a long period on the crest of Pichincha, at an elevation of 14,826 feet. Agassiz spent some weeks in investigations on the Jung-Frau. Gay Lussac attained the highest elevation ever reached by man in his balloon, 28,000 feet. All can recall the thrilling narratives of Arctic voyagers, where the thermometer has been known to measure 91° below zero. Contrast this with the burning sun of India, where 120° Fahrenheit is observed; where glass is cracked by the heat. A wide range of more than 200° of temperature, and yet the heat of the human body maintains its steady and necessary amount, never materially varying under the two extremes. Similiar illustrations of the power of human nature to adapt itself to unnatural conditions might be drawn from all the other elements necessary to life. Notwithstanding this remarkable power of vitality, which can brave such extreme variations in physical conditions and endure enormous privations, careful observation all over our country presents a fearful record of death, sickness, and physical degeneration produced by our own social arrangements--arrangements and habits so destructive to the human organization that they overpower even this great capability of adaptation. This is seen in the statistics of our towns, in the condition of our peasant population, in our social and domestic experience.