Page:Popular Science Monthly Volume 30.djvu/394

378 Quitting the quality of the power given to us to start with, we are next dependent upon the influences derived from the external or surrounding conditions to which we become exposed. Light, air, what we eat and drink, or what in any way gets into the system, temperature, exercise of mind and body—in short, the conditions under which we live—all exert their influence in favoring or otherwise a natural passage through life. Within us, operations forming a part of the operations of Nature proceed, but these operations are influenced by—owe their activity, indeed, to—the surrounding conditions, and thus it is that upon these surrounding conditions depends whether a natural course is run or not. Under the same law, these surrounding conditions may exert a modifying influence in this or that particular direction upon the operations that are proceeding, and by long continuance in force may lead to the establishment of a more or less modified state as a part of our nature, in accordance with the Darwinian principle of natural selection. This matter—the modifications for good or bad, wrought in our nature by the influence of external conditions—embraces a wide field of study, and comprehends nothing less than the possession of a knowledge of the varied operations, with the laws determining them, going on around us, in order that we may understand the manner in which they are brought about. It is a vast subject, but the mind of man has already done much, and there is reason to think will do much more, toward penetrating it; and, as with the amount of knowledge acquired, power is possessed—that is, the power of arranging conditions or operations so as to render them subservient to the production of a desired effect—man stands in the position of an increasingly powerful agent in the realm of Nature. Must not the mind itself, then, through which this is accomplished, be reckoned as a power—a great power among the powers of the universe? In our special department as medical practitioners, it falls to us to apply the power which knowledge gives us toward preventing unnatural conditions of the body from being allowed to become developed, and toward bringing the unnatural back into the natural state—in fact, toward aiding in carrying life on in a natural manner through its ordinary term of existence.—Lancet.



WEET as sugar" and "sour as vinegar" are among the most common comparisons in our language, and the two substances chosen to represent these opposite qualities are popularly deemed as unlike as they can well be. Yet it is one of the marvels of chemistry that the sourest substance with which we are familiar is made from the sweetest. By the action of a ferment, the sugar in some sweet 