view in a different sphere, the essay on the "Genesis of Science" being contributed to the British Quarterly Review in July, 1854. This was primarily called forth by Miss Martineau's "Abridgment of Comte," then just issued, and was in part devoted to the refutation of the French philosopher's views respecting the classification of the sciences. But it became the occasion for a further development of the doctrine of Evolution in its relation to intellectual progress. The whole genesis of science is there traced out historically under the aspect of a body of truths, which, while they became differentiated into different sciences, became at the same time more and more integrated, or mutually dependent, so as eventually to form "an organism of the sciences." There is, besides, a recognition of the gradual increase in definiteness that accompanies this increase in heterogeneity and in coherence.
It was at this time that Mr. Spencer's views on psychology began to assume the character of a system—the conception of intellectual progress now reached being combined with the ideas of life previously arrived at, in the development of a psychological theory. The essay on the "Art of Education," published in the North British Review (May, 1854), assisted in the further development of these ideas. In that essay the conception of the progress of the mind during education is treated in harmony with the conception of mental Evolution at large. Methods are considered in relation to the law of development of the faculties, as it takes place naturally. Education is regarded as rightly carried on only when it aids the process of self-development; and it is urged that the course in all cases followed should be from the simple to the complex, from the indefinite to the definite, from the concrete to the abstract, and from the empirical to the rational.
Having reached this stage in the unfolding of his ideas, Mr. Spencer began the writing of the "Principles of Psychology" in August, 1854. This is a work of great originality, and is important as marking the advance of Mr. Spencer's philosophical views at the time of its preparation. The whole subject of mind is dealt with from the Evolution point of view. The idea which runs through "Social Statics," that there is ever going on an adaptation between living beings and their circumstances, now took on a profounder significance. The relation between the organism and its environing conditions was found to be involved in the very nature of life; and the idea of adaptation was developed into the conception that life itself "is the definite combination of heterogeneous changes, both simultaneous and successive in correspondence with external coexistences and sequences." It is argued that the degree of life varies with the degree of correspondence, and that all mental phenomena ought to be interpreted in terms
- Republished in his little work on "Education," under the title of "Intellectual Education."