Page:Mind (Old Series) Volume 12.djvu/256

THE LOGIC OF CLASSIFICATION. 243 leading classifications of the present day are founded is pre- cisely that which guided the veteran statesman and philo- sopher in the days of Theodoric the Goth. They amply recognise the necessity of commencing with the fundamental and the simple, and of leading onwards, by successive steps, to the dependent and the derived. In carrying out this notion, they present us first of all with the abstract and next with the concrete sciences ; and, in enumerating the branches of each great division, they endeavour to pay due regard to the mutual dependence of the included members. That which is self-sustained or independent comes first ; next comes that which presupposes the principles of this non-dependent science ; then that which requires for its elucidation the principles of both these ; then that which implicates a knowledge of all the three ; and so on. So that, among Abstract sciences, Mathematics is the primary, relying upon none more fundamental than itself, but giving support, to a greater or less extent, to all the others ; then comes Physics, then Chemistry, &c. ; while, among the Concrete sciences, Mineralogy as implying mathematics, physics and chemistry precedes ; Botany and Zoology follow implicating vital and physiological facts ; and so forth. It is all a matter of reasonable sequence : and by thus pursuing the order of dependence and of complexity the most luminous arrangement is obtained, arid the grouping itself becomes highly philosophical. But the great sphere for competing principles is the field of the Classificatory sciences. Both in Zoology and in Botany, where the details are something enormous, it would be strange indeed if only one system were light-giving. Several systems can claim consideration : and the great point is to ascertain which can best bring out the affinities and resemblances ; and this is determined when we have found which classifies according to the greatest number of important characters. This introduces us to the distinction between the Natural and the Artificial systems of classification, a distinction, however, that is not peculiar to the Natural History sciences. It is in reality that which we have already drawn between a rational and an arbitrary or frivolous grouping. The peculiarity of the case lies here that, from the character of the facts manipulated, that system which is known as Artificial is not in any strict sense of the word altogether arbitrary, but must be to a considerable extent also " natural " ; while the system denominated Natural is also to a considerable extent " artificial ".