_Scientific Classification._--Classification, however scientific, is still essentially the process already described. We observe a number of individuals, for example, of our own species. Certain resemblances and differences strike us. Some have straight hair, and copper complexion, others, woolly hair, and black complexion, others, again, differ from the preceding in both these respects. Neglecting minor and specific differences, we fix our attention on the grand points of resemblance, and thus form a general conception, which embraces whatever characteristics belong, in common, to the several individuals which thus resemble each other. To this general conception we appropriate the name Indian, Negro, Caucasian, etc., which henceforth represent to us so many classes or varieties of the human race. Bringing these classes again into comparison with each other, we observe certain points of resemblance between them, and form a conception still more general, that of man. _Further Illustration of the same Process._--In this way the genera and species of science are formed. On grounds of observed resemblance, we class together, for example, certain animals. They differ from each other in color, size, and many other respects, but agree in certain characteristics which we find invariable, as, for example, the form of the skeleton, number of vertebræ, number and form of teeth, arrangement of organs of digestion. We give a name to the class thus formed--carnivora, rodentia, etc. The class thus formed and named, we term the genus, while the minor differences mark the subordinate varieties or species included under the genus. In the same way, comparing other animals, we form other genera. Bringing the several genera also into comparison, we find them likewise agreeing in certain broad resemblances. These points of agreement, in turn, constitute the elements of a conception and classification still wider and more comprehensive than the former. Under this new conception I unite the previous genera, and term them all mammalia. And so on to the highest and widest generalizations of science. Having formed our classification we refer any new specimen to some one of the classes already formed, and the more complete our original survey, the more correct is this process of individual arrangement. It is remarked by Mr. Stewart, that the islanders of the Pacific, who had never seen any species of quadruped, except the hog and the goat, naturally inferred, when they saw a cow, that she must belong to one or the other of these classes. The limitations of human knowledge may lead the wisest philosopher into essentially the same error.