PREFACE. A CONSIDERABLE PART of the following essay formed the subject-matter of a lecture delivered in Leicester last November to the members of the Literary and Philosophical Society, and the public generally of that city. The time appears to me opportune for an appeal in brief form to a still larger public in favour of principles of mental science, of the truth of which a long course of observations, extending over the best years of my life, has rendered me fully convinced. As these years have been chiefly passed in Germany and Austria, the German language and literature have become more familiar to me than those of my father-land. It has been in those countries, moreover, that my collection of casts of the heads of eminent men, criminals, suicides, &c., and of national and other skulls has |