After displaying in the “Études de Mœurs” all the moral and physical transformations through which mankind passes, and after describing the social effects of their natural or civil positions, Balzac sought in the “Études Philosophiques” to demonstrate the causes of these effects; and while the first part of the “Comédie Humaine” contains but a series of individualities typified in the treatment of his subject, in the second part are to be found the same types individualized: as, for example, where in the “Études de Mœurs” Grandet is purely and simply a miser, avarice in the “Études Philosophiques” is incarnated in the person of Maître Cornélius, and the subject, like a sponge, gains in weight what it loses in breadth. The “Études Philosophiques” is the fruit of analyzed comparisons of all the works which the philosophers of antiquity and the specialists of his day had produced on the intellect; and starting with the famous axiom of Jean Jacques Rousseau, that “l’homme qui pense est un animal dépravé,”—an idea which, as is well known, found its poetic interpretation in Byron’s “Manfred,” and its dramatic aspect in the “Faust” of Goethe,—Balzac proceeds to prove that ideas and sentiments are simply dissolvents of a greater or less activity; and taking as his premises the admitted fact that instincts violently excited by factitious or fortuitous circumstances produce unconsciousness and even death, and also that thought, when augmented by the transitory force of passion, may become a poison or a dagger, he infers, from the ravages produced by the intellect, that thought is the most active agent in the disorganization of man, and consequently of society. “Consider,” he says in “Louis Lambert,” “the difference between man who desires nothing and lives like a plant for a hundred years, and the creating artist who suffers early death. Where the sun is, there is thought and brevity of existence; where the cold is, there is torpor and longevity.” Then, after considering man as a simple organization, he brandishes the proposition that vitality decreases in exact proportion to the strength of desire and the dissipation of thought, and leads the reader, therewith, through the gradual development of his theory, which is first attacked in “La Peau de Chagrin.” This weird and fantastic production, in which skepticism and the supernatural join hands, represents the ravages of thought and the supreme expression of egotism as seared by the hot iron of civilization.