Since the time of that philosopher natural history in all its branches has been cultivated with extreme ardour. The writers of this period have been numerous beyond those of any former epoch; and as anatomical investigation was successfully applied to the study of zoology, while the objects known were immensely increased, it was soon found that the classifications of the great reformer of the science were in many respects deficient, and that he had frequently associated objects which have too little affinity to be grouped together in the same class or order. The Systema Naturae, in place of forming a complete catalogue of all the objects of nature, "became," to use the words of an accomplished author, "a mere sketch of what was to be done afterwards. Even more recent naturalists touched with a timid hand upon the natural grouping of the highest branches of the science, and it was reserved for a mighty genius of our own time to open the path to us, and to smooth the difficulties of that path, by precisely determining the limits of the great divisions, by exactly defining the lesser groups, by placing them all according to the invariable characters of their internal structure, and by ridding them of the accumulations of synonymes and absurdities which ignorance, want of method, or fertility of imagination, had heaped upon them."[A] This "mighty genius," it is almost unnecessary to add, was the illustrious Cuvier, who, although by no means the only great, and possibly not even the greatest zoologist of his time, may, if we are disposed to mark an epoch by a single name, be selected for that purpose. But even this celebrated writer has, in his Regne Animal, merely presented a sketch, leaving to others the task of completing the various departments. They who think otherwise forget that the generic and specific characters of the systematist, necessarily condensed, are very inadequate to convey any other than the most superficial knowledge of the diversified objects of nature. These, then, were the men who progressively reared the structure of zoology. Aristotle was a universal genius; but with respect to natural history he is to be looked upon chiefly as a zoologist. Pliny was a collector of every thing known in his time, whether true or fabulous, that related to animals, minerals, and plants. Linnaeus arranged all the objects of nature. He was perhaps greater as a zoologist than as a botanist, although, in the latter capacity, his labours have been more highly appreciated, because there have been more cultivators of the science of plants, of which the study requires less laborious investigation, and to many persons is more attractive. Lastly, Cuvier, an original genius, an acute observer, and an accurate reasoner, profiting by the accumulated knowledge of ages, remodelled the system of zoology, and, in his Regne Animal, arranged the series of animals according to principles elicited from the investigation of their structure and relations.