PREFACE.
IT has never before happened that in the latest edition of a book I have had to disown so much in preceding editions; my first imperfect and spontaneous idea has never before been so modified and transformed, the final form being, perhaps, not even yet altogether attained.
The idea that genius was a special morbid condition had indeed often occurred to me, but I had always repelled it; and besides, without a sure experimental basis, ideas to-day do not count. Like still-born children, they appear but for a moment, to disappear at once. I had been enabled to discover in genius various characters of degeneration which are the foundation and the sign of nearly all forms of congenital mental abnormality, but the exaggerated extension which was at that time given to theories of degeneration, and still more the vague and inexact character of that conception, had repelled me; so that I accepted the facts, but not their ultimate consequences. How, in fact, can one suppress a feeling of horror at the thought of associating with idiots and criminals those individuals who represent the highest manifestations of the human spirit?
But recent teratologic researches, especially those of Gegenbauer, have shown that the phenomena of atavistic retrogression do not always indicate true degradation, but that very often they are simply a compensation for considerable development and progress accomplished in other directions. Reptiles have more ribs than we have; quadrupeds and apes possess more muscles than we do, and an entire organ, the tail, which we lack. It has been in losing these advantages that we have gained our intellectual superiority. When this is seen, the repugnance to
