(103.) There are two modes by which our knowledge of natural history can be successfully prosecuted. The first of these is to commence with investigating the forms and properties of species; combining them, according to their degrees of similarity, into groups or assemblages of different magnitudes; and then attempting to discover what general inferences can be drawn from such combinations, or, in other words, what are the principles by which their variations are regulated. This is the analytical method, by which we commence, as with an alphabet; and from letters determine words; from words proceeding to sentences; and, combining these, again, to chapters. By the second mode, we proceed quite differently. We begin by taking for granted the correctness of certain given principles, and apply them to the investigation and arrangement of some particular group. This is the synthetic mode. By the first, we commence as if all general laws were yet to be discovered; by the latter, as if they were already known, and only required a more particular or extended application.

(104.) As all true knowledge of the combinations of nature must originate in analysis, we shall first intimate how this can be most successfully prosecuted.