The whole ground of human life seems to some to have been gone over by their predecessors, both the heights and the valleys, and all things to have been cared for. According to Evelyn,(22) "the wise Solomon prescribed ordinances for the very distances of trees; and the Roman pr�tors have decided how often you may go into your neighbor's land to gather the acorns which fall on it without trespass, and what share belongs to that neighbor."Hippocrates (23) has even left directions how we should cut our nails; that is, even with the ends of the fingers, neither shorter nor longer. Undoubtedly the very tedium and ennui which presume to have exhausted the variety and the joys of life are as old as Adam. But man's capacities have never been measured; nor are we to judge of what he can do by any precedents, so little has been tried. Whatever have been thy failures hitherto, "be not afflicted, my child, for who shall assign to thee what thou hast left undone?"
 We might try our lives by a thousand simple tests; as, for instance, that the same sun which ripens my beans illumines at once a system of earths like ours. If I had remembered this it would have prevented some mistakes. This was not the light in which I hoed them. The stars are the apexes of what wonderful triangles! What distant and different beings in the various mansions of the universe are contemplating the same one at the same moment! Nature and human life are as various as our several constitutions. Who shall say what prospect life offers to another? Could a greater miracle take place than for us to look through each other's eyes for an instant? We should live in all the ages of the world in an hour; ay, in all the worlds of the ages. History, Poetry, Mythology! � I know of no reading of another's experience so startling and informing as this would be.
 The greater part of what my neighbors call good I believe in my soul to be bad, and if I repent of anything, it is very likely to be my good behavior. What demon possessed me that I behaved so well? You may say the wisest thing you can, old man � you who have lived seventy years, not without honor of a kind � I hear an irresistible voice which invites me away from all that. One generation abandons the enterprises of another like stranded vessels.
 I think that we may safely trust a good deal more than we do. We may waive just so much care of ourselves as we honestly bestow elsewhere. Nature is as well adapted to our weakness as to our strength. The incessant anxiety and strain of some is a well-nigh incurable form of disease. We are made to exaggerate the importance of what work we do; and yet how much is not done by us! or, what if we had been taken sick? How vigilant we are! determined not to live by faith if we can avoid it; all the day long on the alert, at night we unwillingly say our prayers and commit ourselves to uncertainties. So thoroughly and sincerely are we compelled to live, reverencing our life, and denying the possibility of change. This is the only way, we say; but there are as many ways as there can be drawn radii from one centre. All change is a miracle to contemplate; but it is a miracle which is taking place every instant. Confucius (24) said, "To know that we know what we know, and that we do not know what we do not know, that is true knowledge." When one man has reduced a fact of the imagination to be a fact to his understanding, I foresee that all men at length establish their lives on that basis.
 Let us consider for a moment what most of the trouble and anxiety which I have referred to is about, and how much it is necessary that we be troubled, or at least careful. It would be some advantage to live a primitive and frontier life, though in the midst of an outward civilization, if only to learn what are the gross necessaries of life and what methods have been taken to obtain them; or even to look over the old day-books of the merchants, to see what it was that men most commonly bought at the stores, what they stored, that is, what are the grossest groceries. For the improvements of ages have had but little influence on the essential laws of man's existence; as our skeletons, probably, are not to be distinguished from those of our ancestors.
 By the words, necessary of life, I mean whatever, of all that man obtains by his own exertions, has been from the first, or from long use has become, so important to human life that few, if any, whether from savageness, or poverty, or philosophy, ever attempt to do without it. To many creatures there is in this sense but one necessary of life, Food. To the bison of the prairie it is a few inches of palatable grass, with water to drink; unless he seeks the Shelter of the forest or the mountain's shadow. None of the brute creation requires more than Food and Shelter. The necessaries of life for man in this climate may, accurately enough, be distributed under the several heads of Food, Shelter, Clothing, and Fuel; for not till we have secured these are we prepared to entertain the true problems of life with freedom and a prospect of success. Man has invented, not only houses, but clothes and cooked food; and possibly from the accidental discovery of the warmth of fire, and the consequent use of it, at first a luxury, arose the present necessity to sit by it. We observe cats and dogs acquiring the same second nature. By proper Shelter and Clothing we legitimately retain our own internal heat; but with an excess of these, or of Fuel, that is, with an external heat greater than our own internal, may not cookery properly be said to begin? Darwin,(25) the naturalist, says of the inhabitants of Tierra del Fuego, that while his own party, who were well clothed and sitting close to a fire, were far from too warm, these naked savages, who were farther off, were observed, to his great surprise, "to be streaming with perspiration at undergoing such a roasting." So, we are told, the New Hollander (26) goes naked with impunity, while the European shivers in his clothes. Is it impossible to combine the hardiness of these savages with the intellectualness of the civilized man? According to Liebig,(27) man's body is a stove, and food the fuel which keeps up the internal combustion in the lungs. In cold weather we eat more, in warm less. The animal heat is the result of a slow combustion, and disease and death take place when this is too rapid; or for want of fuel, or from some defect in the draught, the fire goes out. Of course the vital heat is not to be confounded with fire; but so much for analogy. It appears, therefore, from the above list, that the expression, animal life, is nearly synonymous with the expression, animal heat; for while Food may be regarded as the Fuel which keeps up the fire within us � and Fuel serves only to prepare that Food or to increase the warmth of our bodies by addition from without � Shelter and Clothing also serve only to retain the heat thus generated and absorbed.