The evolutionist's definition of life is "the continuous adjustment of inner to outer relation," or of organism to environment. The principles and results of this continuous adjustment, in the modifications of structure and function, and their transmission by heredity in gradually more permanently established forms, is well understood from the writings of Mr. Darwin, Mr. Spencer, and others. The progress of development in the human race has consisted in the _establishment of correspondences_ of a definite and permanent character between organism and environment. Why it should have been possible for such a grand development to take place as that which has actually taken place lies beyond the limits of our subject; but if Evolution is true, the fact remains that the human organism has continually been increasing the number of its correspondences, in accordance with the increasing complexity of its surroundings. Roughly, this establishment of relations with the external world may be classed under two divisions, each containing a great variety of details. Firstly, the class of cognitions, including the knowledge of the physical world, the field, the forest, the stream, the animals, the sky and heavenly bodies, and also the knowledge of men, and their ways in society; secondly, the class of direct relations with other individuals, such as the relations of wife, children, parents, chiefs, involving also property, and inducing the feelings of love, friendship, hate, justice, and other social affections. The establishment of a correspondence between the organism and the environment, of such a definite character as to be transmitted by heredity, involves the establishment of motives. The stomach without food experiences hunger, a want, and forms a motive. So of the other organs, and so of all other established relations inwoven in the organism. However subtle and refined any established relation may be, but less in proportion to its later order of development, and directly as its necessity to existence, so its force. It experiences a want in respect of its correlate, and this want becomes a motive or incentive to its own gratification. The kinds of actions, then, may be distinguished as-- The Functional, such as the action of the heart, the intestines, &c. These are wholly involuntary. The Emotional Involuntary, such as the feelings and desires, and the muscular expression of some of them, as in laughing, crying, &c. The Emotional Volitional, or actions proceeding from the emotions, and constraining the muscles to the means of their gratification.