We may here note Mr. Spencer's advanced position in dealing with this subject. While yet the notion of Evolution as a process of Nature was as vague and speculative as it had been in the time of Anaximander and Democritus, he had grasped the problem in its universality and its causes, and had successfully applied it to one of the most difficult and important of the sciences. He had traced the operation of the law in the sphere of mind, and placed that study upon a new basis. The conviction is now entertained by many that the "Principles of Psychology," by Spencer, in 1855, is one of the most original and masterly scientific treatises of the present century, if, indeed, it be not the most fruitful contribution to scientific thought that has appeared since the "Principia" of Newton. For thousands of years, from Plato to Hamilton, the world's ablest thinkers had been engaged in the effort to elucidate the phenomena of mind; Herbert Spencer took up the question by a method first rendered possible by modern science, and made a new epoch in its progress. From this time forward, mental philosophy, so called, could not confine itself to introspection of the adult human consciousness. The philosophy of mind must deal with the whole range of psychical phenomena, must deal with them as manifestations of organic life, must deal with them genetically, and show how mind is constituted in connection with the experience of the past. In short, as it now begins to be widely recognized, Mr. Spencer has placed the science of mind firmly upon the ground of Evolution. Like all productions that are at the same time new and profound, and go athwart the course of long tradition, there were but few that appreciated his book, a single small edition more than sufficing to meet the wants of the public for a dozen years. But it began at once to. tell upon advanced thinkers, and its influence was soon widely discerned in the best literature of the subject. The man who stood, perhaps, highest in England as a psychologist, Mr. John Stuart Mill, remarked in one of his books, that "it is one of the finest examples we possess of the psychological method in its full power;" and, as I am aware, after carefully rereading it some years later, he declared that his already high opinion of the work had been raised
- This association of the name of Spencer with Newton, let it be remembered, does not rest upon the authority of the present writer; recent discussions of the subject in the highest quarters are full of it. The Saturday Review says, "Since Newton there has not in England been a philosopher of more remarkable speculative and systematizing talent than (spite of some errors and some narrowness) Mr. Herbert Spencer." An able writer in the Quarterly Review, in treating of Mr. Spencer's remarkable power of binding together different and distant subjects of thought by the principle of Evolution, remarks: "The two deepest scientific principles now known of all those relating to material things are the Law of Gravitation and the Law of Evolution." The eminent Professor of Logic in Owens College, Manchester, Mr. W. Stanley Jevons, in his recent treatise entitled "The Principles of Science, a Treatise on Logic and Scientific Method," says, "I question whether any scientific works which have appeared, since the 'Principia' of Newton, are comparable in importance with those of Darwin and Spencer, revolutionizing as they do all our views of the origin of bodily, mental, moral, and social phenomena."