Preface to the Original Edition The idea of investigating the subject of hereditary genius occurred to me during the course of a purely ethnological inquiry, into the mental peculiarities of different races; when the fact, that characteristics cling to families, was so frequently forced in my notice as to induce me to pay especial attention to that branch of the subject. I began by thinking over the dispositions and achievements of my contemporaries at school, at college, and in after life, and was surprised to find how frequently ability seemed to go by descent. Then I made a cursory examination into the kindred of about four hundred illustrious men of all periods of history, and the results were such, in my own opinion, as completely to establish the theory that genius was hereditary, under limitations that required to be investigated. Thereupon I set to work to gather a large amount of carefully selected biographical data, and in the meantime wrote two articles on the subject, which appeared in [italics]Macmillan's Magazine[end italics] in June and in August, 1865. I also attacked the subject from many different sides and sometimes with very minute inquiries, because it was long before the methods I finally adopted were matured. I mention all this, to show that the foundation [end]