Lewes did not confine himself to philosophy. Other and very different subjects also attracted his attention. His mind ranged in many directions, and his flexible genius found subjects of interest on all sides. In 1846 he published a little book on The Spanish Drama: Lope de Vega and Calderon, a slight affair, full of his peculiar prejudices, and devoted mainly to an unsympathetic criticism. The following year he gave to the world an ambitious novel, Ranthorpe. It seems to have been well read in its day, was translated into German and reprinted on the continent by Tauchnitz. The plot is well conceived, but the story is rapidly told, full of incident and tragedy, and there is a subtle air of unreality about it. The experiences of a poet are unfolded in a romantic form, and the attempt is made to show what is the true purpose and spirit in which literature can be successfully pursued. To this end there is a discussion running through the book on the various phases of the literary life, much in the manner of Fielding. Ranthorpe would now be regarded as a very dull novel, and it is crude, full of the sensational, with little analysis of character and much action.
It was read, however, by Charlotte Brontë with great interest, and she wrote of it to the author in these words: "In reading Ranthorpe I have read a new book—not a reprint—not a reflection of any other book, but a new book. I did not know such books were written now. It is very different to any of the popular works of fiction; it fills the mind with fresh knowledge. Your experience and your convictions are made the reader's; and to an author, at least, they have a value and an interest quite unusual." In 1848, Lewes published another novel of a very different kind—Rose, Blanche and Violet. This was a society novel, intended to reach the minds of the ordinary novel-readers, but was not so successful as the first. It has little plot or incident, but has much freshness of thought and originality of style.
The same year appeared his Life of Robespierre, the result of original investigations, and based largely on unpublished correspondence. Without any sympathy of opinion with Robespierre, and without any purpose of vindicating his character, Lewes told the true story of his life, and showed wherein he had been grossly misrepresented. The book was one of much interest, though it lacked in true historic insight and was clumsily written. While these works were appearing, Lewes was a voluminous contributor to the periodical literature of the day. He wrote, at this time and later, for the Edinburgh Review, the Foreign Quarterly, British Quarterly, Westminster Review, Fraser's Magazine, Blackwood's Magazine, Cornhill Monthly, Saturday Review, in the Classical Museum, the Morning Chronicle, the Atlas and various other periodicals, and on a great variety of subjects. His work of this kind was increased when in 1849 he became the literary editor of The Leader newspaper, a weekly journal of radical thought and politics. His versatility, freshness of thought and vigor of expression made this department of The Leader of great interest. His reviews of books were always good, and his literary articles piquant and forcible. In the first volume he published a story called The Apprenticeship of Life. In April, 1852, he began in its columns a series of eighteen articles on Comte's Positive Philosophy. In connection with the second article of this series he asked for subscriptions in aid of Comte, and in the third reported that three workingmen had sent in money. These subscriptions were continued while the articles were in progress, and amounted to a considerable sum. In 1854 these essays were republished in Bohn's Scientific Library under the title of Comte's Philosophy of the Sciences. The Leader was ably conducted, but it was radical and outspoken, and did not receive the support it deserved. In 1854 his connection with it came to an end.
While connected with The Leader, Lewes had turned his attention to Goethe, and made a thorough study of his life and opinions. After spending many months in Weimar, and as a result of his studies in Germany, he published in 1855 his Life and Works of Goethe. It was carefully re-written in 1873, and the substance of it was given in an abbreviated and more popular form a few years later. This has usually been accepted as the best book about Goethe written in English. Mr. Anthony Trollope expresses the usual opinion when he says, "As a critical biography of one of the great heroes of literature it is almost perfect. It is short, easily understood by common readers, singularly graphic, exhaustive, and altogether devoted to the subject." On the other hand, Bayard Taylor said that "Lewes's entertaining apology hardly deserves the name of a biography." It is an opinionated book, controversial, egotistic, and unnecessarily critical. It was written less with the purpose of interpreting Goethe to the English reader than of giving expression to Lewes's own views on many subjects. His chapters on Goethe's science and on his realism are marked by an extreme dogmatism. The poetic and religious side of Goethe's nature he was incapable of understanding, and always misrepresents, as he did that side of his nature which allied Goethe with Schiller and the other idealists. Lewes was always polemical, had some theory to champion, some battle to fight. He did not write for the sake of the subject, but because the subject afforded an arena of battle for the theories to the advocacy of which he gave his life.
With the completion of his Life of Goethe, Lewes turned his attention more than ever to physiological studies, though he had continued to give them much attention in the midst of his other pursuits. In 1858 appeared his Seaside Studies, in which he recorded the results of his original investigations at Ilfracombe, Tenby, Scilly Isles and Jersey. This volume is written in a plain descriptive style, containing many interesting accounts of scenery and adventure, explanations of the methods of study of animal life at the seashore, how experiments are carried on, the results of these special studies, and much of controversy with other observers. It combines science and description in a happy manner. Another result of his physiological studies was a paper "On the Spinal Cord as a Centre of Sensation and Volition," read before the British Association for the Advancement of Science, in 1858. This was followed the next year by three published addresses on "The Nervous System," in which he presented those theories which were more carefully developed in his latest work, where he gave a systematic account of his philosophy. From this time on to his death the greater part of his energies were given to these studies, and to the building up of a philosophy based on physiology. A popular work, in which many of his theories are unfolded, and marked throughout by his peculiar ideas in regard to the relations of body and mind, was published in 1858. This was his Physiology of Common Life, a work of great value, and written in a simple, comprehensive style, suited to the wants of the general reader. In the first volume he wrote of hunger and thirst, food and drink, digestion, structure and uses of the blood, circulation of the blood, respiration and suffocation, and why we are warm and how we keep so. The second treats of feeling and thinking, the mind and the brain, our senses and sensations, sleep and dreams, the qualities we inherit from our parents, and life and death. In 1860 he printed in The Cornhill Magazine a series of six papers on animal life. They were reprinted in book form in 1861, under the title of Studies in Animal Life. More strictly scientific than his Seaside Studies, they were even more popular in style, and intended for the general reader. While these books were being published he was at work on a more strictly scientific task, and one intended for the thoughtful and philosophic reader. This was his Aristotle: a Chapter from the History of Science, including Analyses of Aristotle's Scientific Writings, which was completed early in 1862, but not published until 1864. As in his previous works, Lewes is here mainly concerned with an exposition of his theories of the inductive method, and he judges Aristotle from this somewhat narrow position. He refuses Aristotle a place among scientific observers, but says he gave a great impulse towards scientific study, while in intellectual force he was a giant. The book contains no recognition of Aristotle's value as a philosopher; indeed his metaphysics are treated with entire distrust or indifference. His fame is pronounced to be justifiably colossal, but it is said he did not lay the basis of any physical science. It is a work of controversy rather than of unbiassed exposition, and its method is dry and difficult.
Early in the year 1865, a few literary men in London conceived the project of a new review, which should avoid what they conceived to be the errors of the old ones. It was to be eclectic in its doctrinal position, contain only the best literature, all articles were to be signed by the author's name, and it was to be published by a joint-stock company. Lewes was invited to become the editor of this new periodical, and after much urging he consented. The first number of The Fortnightly Review was published May 15,1865, It proved a financial failure, and was soon sold to a publishing firm. The eclectic theory was abandoned, and the Review became an agnostic and radical organ under the management of its second editor, John Morley. Lewes edited six volumes, when, in 1867, he was obliged, on account of his health, to resign his position. He made the Review an independent and able exponent of current thought, and he kept it up to a very high standard of literary excellence. His own contributions were among the best things it contained, and give a good indication of the wide range of his talent. In the first volume he published papers on "The Heart and the Brain," and on the poetry of Robert Buchanan, as well as a series of four very able and valuable papers on "The Principles of Success in Literature." In the second volume he wrote about "Mr. Grote's Plato." In the third he dealt with "Victor Hugo's Latest Poems," "Criticism in relation to Novels," and "Auguste Comte." In this volume he began a series of essays entitled "Causeries," in which he treated, in a light vein, of the passing topics of the day. He wrote of Spinoza in the fourth volume, and of "Comte and Mill" in the sixth, contributing nothing to the fifth. After Morley became the editor, in the ninth and tenth volumes, he published three papers on Darwin's hypothesis, and in 1878 there was a paper of his on the "Dread and Dislike of Science." He also had a criticism of Dickens in the July number of 1872, full of his subtle power of analysis and literary insight.
Lewes in early life had a strong inclination to become an actor, and he did go on the stage for a short time. He wrote and translated several plays, one of his adaptations becoming very popular. He wrote dramatic criticisms for the Pall Mall Gazette and other journals, during many years. In 1875, a volume of these papers was published with the title, On Actors and the Art of Acting. It treated in a pleasant way, and with keen insight, of Edmund Kean, Charles Kean, Rachel, Macready, Fan-en, Charles Matthews, Frédéric Lemaitre, the two Keeleys, Shakspere as actor and critic, natural acting, foreign actors on our stage, the drama of Paris in 1865, Germany in 1867, and Spain in 1867, and of his first impressions of Salvini. Another piece of work done by him was the furnishing, in 1867, of an explanatory text to accompany Kaulbach's Female Characters of Goethe.
The last years of Lewes's life were devoted to the preparation of a systematic exposition of his physiological philosophy. As early as the year 1858, he was at work on the nervous system, and, soon after, his studies took a systematic shape. In his series of volumes on the Problems of Life and Mind he gave to the world a new theory of the mind and of knowledge. In the first two volumes, published in 1874, and entitled The Foundations of a Creed, he developed his views on the methods of philosophic research. These were followed in 1877 by a third volume, on The Physical Basis of Life. After his death his wife edited two small volumes on Psychology, which included all the writing he left in a form ready for publication. His work was left incomplete, but its publication had gone far enough to show the methods to be followed and the main conclusions to be reached.
Concerning the work done by Lewes in philosophy, there will be much difference of opinion. He did much through his various expositions to make the public familiar with the inductive methods of inquiry and with the conclusions of positive thought. He made his books readable, and even popular, giving philosophy an exposition suited to the wants of the general reader. At the same time, he was polemical and dogmatic, and more concerned to be clever than to be exact in his interpretation. Into the meanings of some of the greatest thinkers he had little clear insight, and he is seldom to be implicitly trusted as an expositor of those whose systems were in any way opposed to his own. His limitations have been well defined by Ribot, in his Contemporary English Psychology.
"Mr. Lewes lacks the vocation of the scholar, which, indeed, is generally wanting in original minds. His history resembles rather that of Hegel than that of Ritter. His review of the labors of philosophers is rather occupied with that which they have thought, than with their comparative importance. He judges rather than expounds; his history is fastidious and critical. It is the work of a clear, precise and elegant mind, always that of a writer, often witty, measured, possessing no taste for declamation, avoiding exclusive solutions, and making its interest profitable to the reader whom he forces to think." Ribot speaks of the work again as being original but dogmatic and critical. He says it belongs to that class of books which make history a pretext for conflict. "The author is less occupied with the exposition of facts than he is with his method of warfare; he thinks less of being exact than of being clever…. He has evidently no taste, or, if we prefer so to put it, he has not the virtue necessary to face these formidable folios, these undigested texts of scholastic learning, which the historian of philosophy ought to penetrate, however repulsive to his positive and lucid mind."