The second aspect of the study of nature, which we have designated as philosophical, regards the logic of nature, or what the older writers spoke of as General Physiology. This is sometimes appropriately termed Natural Philosophy, a designation which is the correlative of Natural History. With this method of study in the organic kingdoms we are familiar under the names of physiological botany and physiological zoölogy, which concern themselves with anatomy, organography, and morphology, and with the processes of growth, nutrition, and decay in organized existences. The natural philosophy of the inorganic world investigates the motions and the energies of the heavenly bodies, and then, coming down to our planet, considers all the phenomena which come under the head of dynamic or physic, as well as those of chemistry. These various activities together "constitute the secular life of our planet. They are the geogenic agencies which in the course of ages have molded the mineral mass of the earth, and from primeval chaos have evolved its present order, formed its various rocks, filled the veins in its crust with metals, ores, gems, and spars, and determined the composition of its waters and its atmosphere. They still regulate alike the terrestrial, the oceanic, and the aerial circulation, and preside over the constant change and decay by which the surface of the earth is incessantly renewed and the conditions necessary to organic life are maintained." Thus the physiological study of the inorganic world, or in other words its natural philosophy, includes in its scope at once theoretical astronomy and theoretical geology or geogeny.
The twofold division which has been adopted in the scientific class of our new society does not correspond to that which we have just set forth, namely, of Natural History on the one hand and Natural Philosophy on the other; nor yet, as might at first seem to be the case, to the more familiar distinction between inorganic and organic nature. Our Section III has been made to embrace, it is true, much both of the natural history and the natural philosophy of the inorganic world, including, besides physic and chemistry, both descriptive and theoretical astronomy and mineralogy. This same section has also been made to include mathematic, which in itself does not belong to the domain of natural science, though in its applications it becomes an indispensable instrument in the study of nature; whether we investigate the phenomena of physic or of chemistry, or seek to comprehend the laws which regulate alike the order of the celestial spheres, the shapes of crystals, and the forms of vegetation.
Section IV, on the other hand, in its department of biology, includes alike the natural history and the natural philosophy of the vegetable and the animal kingdoms. In this same section has, how-
- "The Domain of Physiology, or Nature in Thought and Language," by T. Sterry Hunt, "London, Edinburgh, and Dublin Philosophical Magazine" (vol. xii, pp. 233-253) for October, 1881; also separately reprinted, pp. 28; S. E. Cassino: Boston, 1882.