On this account also he confounds everything in his researches in an undistinguishable mass, vegetative and medicinal properties, mechanical and curative, physical and moral, without considering the most complex as depending on the simplest, but each on the contrary in itself, and taken apart, as an irreducible and independent existence. Obstinate in this error, the thinkers of the age mark time without advancing. They see clearly with Bacon the wide field of discovery, but they cannot enter upon it. They want an idea, and for want of this idea they do not advance. The disposition of mind which but now was a lever, is become an obstacle: it must be changed, that the obstacle may be got rid of. For ideas, I mean great and efficacious ones, do not come at will nor by chance, by the effort of an individual, or by a happy accident. Methods and philosophies, as well as literatures and religions, arise from the spirit of the age; and this spirit of the age makes them potent or powerless. One state of public intelligence excludes a certain kind of literature; another, a certain scientific conception. When it happens thus, writers and thinkers labor in vain, the literature is abortive, the conception does not make its appearance. In vain they turn one way and another, trying to remove the weight which hinders them; something stronger than themselves paralyzes their hands and frustrates their endeavors. The central pivot of the vast wheel on which human affairs move must be displaced one notch, that all may move with its motion. At this moment the pivot was moved, and thus a revolution of the great wheel begins, bringing round a new conception of nature, and in consequence that part of the method which was lacking. To the diviners, the creators, the comprehensive and impassioned minds who seized objects in a lump and in masses, succeeded the discursive thinkers, the systematic thinkers, the graduated and clear logicians, who, disposing ideas in continuous series, lead the hearer gradually from the simple to the most complex by easy and unbroken paths. Descartes superseded Bacon; the classical age obliterated the Renaissance; poetry and lofty imagination gave way before rhetoric, eloquence, and analysis. In this transformation of mind, ideas were transformed. Everything was drained dry and simplified. The universe, like all else, was reduced to two or three notions; and the conception of nature, which was poetical, became mechanical. Instead of souls, living forces, repugnances, and attractions, we have pulleys, levers, impelling forces. The world, which seemed a mass of instinctive powers, is now like a mere machinery of cog-wheels. Beneath this adventurous supposition lies a large and certain truth; that there is, namely, a scale of facts, some at the summit very complex, others at the base very simple; those above having their origin in those below, so that the lower ones explain the higher; and that we must seek the primary laws of