Herbert Spencer was born on April 27, 1820, at Derby, in England, and was an only surviving child. His father was a schoolmaster in the town named, and secretary of a philosophical society. From him the son seems to have imbibed the love of natural science and the faculty of observation conspicuous in his work. The father was particularly interested in entomology, and Spencer himself used to collect, describe, and draw insects when a boy. At the age of thirteen he was sent to study with an uncle, Rev. Thomas Spencer, a liberal clergyman and a scholar, with whom he remained three years, carrying on the study of natural history, which he had begun in childhood. He now devoted himself to mathematics, evincing a singular capacity for working out original problems. At this time, too, he became familiar with physical and chemical investigations, and already exhibited a strong tendency to experimental inquiry and original research. His aversion to linguistic studies put a university career out of the question. At the age of seventeen he entered the office of Sir Charles Fox and began work as a civil engineer, but about eight years afterward he gave up this profession, and devoted the whole of his time to scientific experiments and studies, and to contributions on philosophical questions to various periodicals. As early as 1842, in a series of letters to the Nonconformist newspaper on "The Proper Sphere of Government," he propounded a belief in human progress based on the modifiability of human nature through adaptation to its social surroundings, and he asserted the tendency of these social arrangements to assume of themselves a condition of stable equilibrium. From 1848 to 1853 he was sub-editor of the Economist newspaper, and in his first important work, "Social Statics," published in 1850, he developed the ethical and sociological ideas which had been set forth in his published letters. The truth that all organic development is a change from a state of homogeneity to a state of heterogeneity is regarded by Spencer as the organizing principle of his subsequent beliefs. It was gradually expounded and applied by him in a series of articles contributed to the "North British," the "British Quarterly," the "Westminster," and other reviews. In these essays, and especially in the volume of "Principles of Psychology," published in 1855, the doctrine of Evolution began to take definite form, and to be applied to various departments of inquiry. It was not until four years later--a fact to be carefully borne in mind by those who would estimate correctly the relation of Spencer to Darwin--that the publication of the latter's "Origin of Species" afforded a wide basis of scientific truth for what had hitherto been matter of speculation, and demonstrated the important part played by natural selection in the development of organisms. As early as March, 1860, Spencer issued a prospectus, in which he set forth the general aim