The prospectus of the then proposed issue of the series of works which, beginning with First Principles, ends with the Principles of Sociology (1862-1896), was issued by Mr. Spencer in March, 1860. Through his courtesy the writer has seen the documents which prove that the first draft of that prospectus was written out on the 6th of January, 1858, and that it was the occasion of an interesting correspondence between Mr. Spencer and his father--mainly in the form of questions from the latter--during that month. The record of these facts is of some moment as evidencing that the scheme of the Synthetic Philosophy took definite shape in 1857. Therefore, the Theory of Evolution, dealing with the universe _as a whole_, was formulated some months before the publication of the Darwin-Wallace paper, in which only _organic evolution_ was discussed. The Origin of Species, as the outcome of that paper, showed that the action of natural selection is a sufficing cause for the production of new life-forms, and thus knocked the bottom out of the old belief in special creation. The general doctrine of Evolution, however, is not so vitally related to that of natural selection that the two stand or fall together. The evidence as to the connection between the succession of past life-forms which, regard being had to the well-nigh obliterated record, has been supplied by the fossil-yielding rocks; and the evidence as to the unbroken development of the highest plants and animals from the lowest which more and more confirms the theory of Von Baer; alike furnish a body of testimony placing the doctrine of Organic Evolution on a foundation that can never be shaken. And, firm as that, stands the doctrine of Inorganic Evolution upon the support given by modern science to the speculations of Immanuel Kant.