Literary history is, in its profoundest significance, psychology, the study, the history of the soul. A book which belongs to the literature of a nation, be it romance, drama, or historical work, is a gallery of character portraits, a storehouse of feelings and thoughts. The more momentous the feelings, the greater, clearer, and wider the thoughts, the more remarkable and at the same time representative the characters, so much the greater is the historical value of the book, so much the more clearly does it reveal to us what was really happening in men's minds in a given country at a given period. Regarded from the merely æsthetic point of view as a work of art, a book is a self-contained, self-existent whole, without any connection with the surrounding world. But looked at from the historical point of view, a book, even though it may be a perfect, complete work of art, is only a piece cut out of an endlessly continuous web. Æsthetically considered, its idea, the main thought inspiring it, may satisfactorily explain it, without any cognisance taken of its author or its environment as an organism; but historically considered, it implies, as the effect implies the cause, the intellectual idiosyncrasy of its author, which asserts itself in all his productions, which conditions this particular book, and some understanding of which is indispensable to its comprehension. The intellectual idiosyncrasy of the author, again, we cannot comprehend without some acquaintance with the intellects which influenced his development, the spiritual atmosphere which he breathed. The intellectual phenomena which condition, elucidate, and explain each other, fall of themselves into natural groups.