_Homo sum: humani nihil a me alienum puto_: "I am a man and nothing human is foreign to me." This oft-quoted saying of the old farmer in the Self-Tormentor of Terence might be affixed as motto to Herbert Spencer's writings from the tractate on the Proper Sphere of Government to the concluding volume of the Principles of Sociology. For thought of human interests everywhere pervades them; social and ethical questions are kept in the van throughout. Philosophy is brought from her high seat to mix in the sweet amenities of home, in the discipline of camp, in the rivalry of market; and linked to conduct. Conduct is defined as "acts adjusted to ends," the perfecting of the adjustment being the highest aim, so that "the greatest totality of life in self, in offspring, and in fellow-men" is secured, the limit of evolution of conduct not being reached, "until, beyond avoidance of direct and indirect injuries to others, there are spontaneous efforts to further the welfare of others." Emerson puts this ideal into crisp form when he speaks of the time in which a man shall care more that he wrongs not his neighbour than that his neighbour wrongs him; then will his "market-cart become a chariot of the sun." That humanity is the pivot round which Mr. Spencer's philosophic system revolves is seen in the earliest Essays, and notably in his making mental evolution the subject of the first instalment of his Synthetic Philosophy. For, in the Principles of Psychology, published in 1855, he limits feeling or consciousness to animals possessing a nervous system, and traces its beginnings in the "blurred, undetermined feeling answering to a single pulsation or shock" (as for example, to go no lower down the life-scale, in the medusa or jelly-fish), to its highest form as self-consciousness, or knowing that we know, in man. This dominant element in Mr. Spencer's philosophy secures it a life and permanence which, had it been restricted to explaining the mechanics of the inorganic universe, it could never have possessed. It has been observed how the Darwinian theory aroused attention in all quarters because it touched human interests on every side. And, although less obvious to the multitude, the Synthetic Philosophy, dealing with all cosmic processes as purely mechanical problems, interprets "the phenomena of life (excluding the question of its origin), mind, and society, in terms of matter and motion." Anticipating the levelling of epithets against such apparent materializing of mental phenomena involved in that method, Spencer remarks on the dismay with which men, who have not risen above the vulgar conception which unites with matter the contemptuous epithets "gross" and "brute," regard the proposal to reduce the phenomena of Life, of Mind, and of Society, to a level which they think so degraded. "Whoever remembers that the forms of existence which the uncultivated speak of with so much scorn, are shown by the