Nature has no unit of magnitude by which she measures her works. Man takes his standards of dimension from himself. The hair's breadth was his minimum until the microscope told him that there are animated creatures to which one of the hairs of his head is a larger cylinder than is the trunk of the giant California redwood to him. He borrows his inch from the breadth of his thumb, his palm and span from the width of his hand and the spread of his fingers, his foot from the length of the organ so named; his cubit is the distance from the tip of his middle finger to his elbow, and his fathom is the space he can measure with his outstretched arms. To a being who instinctively finds the standard of all magnitudes in his own material frame, all objects exceeding his own dimensions are absolutely great, all falling short of them absolutely small. Hence we habitually regard the whale and the elephant as essentially large and therefore important creatures, the animalcule as an essentially small and therefore unimportant organism. But no geological formation owes its origin to the labors or the remains of the huge mammal, while the animalcule composes, or has furnished, the substance of strata thousands of feet in thickness, and extending, in unbroken beds, over many degrees of terrestrial surface. If man is destined to inhabit the earth much longer, and to advance in natural knowledge with the rapidity which has marked his progress in physical science for the last two or three centuries, he will learn to put a wiser estimate on the works of creation, and will derive not only great instruction from studying the ways of nature in her obscurest, humblest walks, but great material advantage from stimulating her productive energies in provinces of her empire hitherto regarded as forever inaccessible, utterly barren.[111] CHAPTER III. THE WOODS. THE HABITABLE EARTH ORIGINALLY WOODED--THE FOREST DOES NOT FURNISH FOOD FOR MAN--FIRST REMOVAL OF THE WOODS--EFFECTS OF FIRE ON FOREST SOIL--EFFECTS OF THE DESTRUCTION OF THE FOREST--ELECTRICAL INFLUENCE OF TREES--CHEMICAL INFLUENCE OF THE FOREST. INFLUENCE OF THE FOREST, CONSIDERED AS INORGANIC MATTER, ON TEMPERATURE: _a_, ABSORBING AND EMITTING SURFACE; _b_, TREES AS CONDUCTORS OF HEAT; _c_, TREES IN SUMMER AND IN WINTER; _d_, DEAD PRODUCTS OF TREES; _e_, TREES AS A SHELTER TO GROUNDS TO THE LEEWARD OF THEM; _f_, TREES AS A PROTECTION AGAINST MALARIA--THE FOREST, AS INORGANIC MATTER, TENDS TO MITIGATE EXTREMES. TREES AS ORGANISMS: SPECIFIC TEMPERATURE--TOTAL INFLUENCE OF THE FOREST ON TEMPERATURE.