INTRODUCTION.
For the fifth time I revise a subject which has occupied my inquiries from early life, with feelings still delightful, and an enthusiasm not wholly diminished.
Had not the principle upon which this work is constructed occurred to me in my youth, the materials which illustrate the literary character could never have been brought together.

It was in early life that I conceived the idea of pursuing the history of genius by the similar events which had occurred to men of genius.

Searching into literary history for the literary character formed a course of experimental philosophy in which every new essay verified a former trial, and confirmed a former truth.

By the great philosophical principle of induction, inferences were deduced and results established, which, however vague and doubtful in speculation, are irresistible when the appeal is made to facts as they relate to others, and to feelings which must be decided on as they are passing in our own breast.
It is not to be inferred from what I have here stated that I conceive that any single man of genius will resemble every man of genius; for not only man differs from man, but varies from himself in the different stages of human life.

All that I assert is, that every man of genius will discover, sooner or later, that he belongs to the brotherhood of his class, and that he cannot escape from certain habits, and feelings, and disorders, which arise from the same temperament and sympathies, and are the necessary consequence of occupying the same position, and passing through the same moral existence.