It may be observed with respect to the method followed by Linnaeus in his arrangements, that he has generally chosen the most simple and perspicuous that he could devise. The whole creation he disposes into three _kingdoms_, the animal, the vegetable, and the mineral. The animal kingdom is divided into six great _classes_, characterized by various circumstances of their organization. Each of these six classes is divided into several _orders_ and numerous _genera_; and the genera are composed of _species_. Sometimes the species exhibits _varieties_, or variations of form, colour, and other qualities, dependent upon climate, food, domestication, and other circumstances. There are thus in his arrangement of animals five gradations: kingdom, class, order, genus, and species. We shall find that the same series is adopted in his classification of the vegetable kingdom. It must be remarked, however, that in nature none of these gradations actually exist. Individuals alone form the subjects of observation; but a number of individuals closely resembling each other are considered in the mind as forming a species; and several species agreeing in certain respects with each other form a genus; while genera united by particular characters compose an order; and the orders constitute a class. Thus all the individual birds called goldfinches form the species _Goldfinch_, which with the species _Chaffinch_ and others constitute the genus _Finch_. This genus, and those known by the names of _Grossbeak_, _Bunting_, _Lark_, &c. constitute the order _Passerine Birds_. Natural objects may thus be arranged in a definite series, so that the place of any given species may be determined; hence, if the student should be desirous of finding the name and history of a particular object, he can readily discover it, or he can satisfy himself that it has not yet been described. At the same time, it must be remembered, that the classification in question is entirely artificial, and does not necessarily place together genera that are the most closely allied. It is a kind of systematic index to the works of nature, and is useful in many respects, although it may not lead to the disclosure of all the peculiarities or all the affinities and relations of the object to be examined. The Linnaean arrangement of animals cannot be considered in any other light; for, if we view it as a natural classification, we meet with false positions and erroneous views at almost every step. His disciples mistook it for a perfect system, and viewed the various species with reference to it, rather than with respect to their mutual relations. Still, they who look upon the artificial classifications of our great master as having done more harm than good, judge erroneously; for although they are certainly imperfect, without them or others of a similar kind it would have been impossible to retain any distinct remembrance of the numerous objects which have successively been introduced to notice.