The sixth member of this club, who "studied anatomy and many other things, with vast aspirations, and no very definite career before him," was Lewes himself, in all probability. His eager desire for knowledge took him to Germany in 1838, where he remained for two years in the same desultory study of many subjects. He became thoroughly acquainted with the German language and life, and gave much attention to German literature and philosophy. On his return to England, Lewes entered upon his literary career, which was remarkable for its versatility and productiveness. In 1841 he wrote "The Noble Heart," a three-act tragedy, published in 1852. His studies of Spinoza found expression in one of the first essays on the subject published in England. In 1843, he published in the _Westminster Review_ his conclusions on that thinker. His essay was reprinted in a separate form, attracting much attention, and in 1846 was incorporated into a larger work, the result of his studies in Germany and of his interest in philosophy. In 1845, at the age of twenty-nine, he published a history of philosophy, in which he undertook to criticise all metaphysical systems from the inductive and scientific point of view. This work was his _Biographical History of Philosophy_. It appeared in four small volumes in Knight's weekly series of popular books devoted to the diffusion of knowledge among the people. Lewes touched a popular demand in this book, reaching the wants of many readers. He continued through many years to elaborate his studies on these subjects and to re-work his materials. New and enlarged editions, each time making the book substantially a new one, were published in 1857, in 1867 and in 1871. No solid book of the century has sold better; and it has been translated into several continental languages.