Malthus and Doubleday published their works, that is, the principles of the science in many of their most practical applications. In fact, it may safely be said that some of these principles, as far as their application is concerned, are still in their infancy. One of the most interesting and important of these applications will be found, we believe, in establishing a general law of human increase.
After many years of study, observation, and reflection, we have been led to believe that there is such a law, and propose to submit some of the facts and arguments upon which this belief is based. As the subject is so vast and complicated, a large volume would be required to discuss it properly; we can present here only a few points or heads of topics, by way of argument and illustration. In order to present a clear and connected view in a short paper, few quotations or references will be given.
What, then, is the briefest definition that can be given of this law? It consists in the 'perfectionism of structure and harmony of function; or, in other words, that every organ in the body should be perfect in its structure, and that each should perform its legitimate function in harmony with all others. Though this perfect physical organization is nowhere to be found in nature, we can readily conceive of such a standard, and that there may be all manner of approximations toward it. The nearer this standard is reached, the more completely the law of propagation will be carried out. Such a basis harmonizes with the great fundamental or general laws of Nature, as we find that they are all based upon the highest or most perfect development of her works. Any other basis or lower standard would reflect upon the Creator of all things, and interfere with the harmony and order which exist in Nature's operations. Thus, in reference to every organ in the human body, there is such a thing as a normal, perfect structure, and, wherever this exists, they constitute a perfect model or standard for the whole system. All diseases interfere at once with the operations of this law, especially those that are considered hereditary. This class of diseases changes with each generation, and sometimes becomes so intensified that they impair the vitality and strength of the system to such an extent as to prevent propagation. There is a class of diseases or weaknesses, described under the head of "sterility," "barrenness," and "impotence," from which strong evidence may be deduced in proof of a general law of increase.
There is a law in physiology, favorable to this theory, described by Dr. Carpenter thus: "There is a certain antagonism between the nutritive and reproductive functions, the one being exercised at the expense of the other. The reproductive apparatus derives the materials of its operations through the nutritive system and its functions. If, therefore, it is in a state of excessive activity, it will necessarily draw off from the individual fabric some portion of aliment destined for its maintenance. It may be universally observed that, when the