All rational knowledge is either material or formal:  the former considers some object, the latter is concerned only with the form of the understanding and of the reason itself, and with the universal laws of thought in general without distinction of its objects.  Formal philosophy is called Logic.  Material philosophy, however, which has to do with determinate objects and the laws to which they are subject, is again two-fold; for these laws are either laws of nature or of freedom.  The science of the former is Physics, that of the latter, Ethics; they are also called natural philosophy and moral philosophy respectively.

Logic cannot have any empirical part; that is, a part in which the universal and necessary laws of thought should rest on grounds taken from experience; otherwise it would not be logic, i. e. a canon for the understanding or the reason, valid for all thought, and capable of demonstration.  Natural and moral philosophy, on the contrary, can each have their empirical part, since the former has to determine the laws of nature as an object of experience; the latter the laws of the human will, so far as it is affected by nature:  the former, however, being laws according to which everything does happen; the latter, laws according to which everything ought to happen. [Footnote:  The word “law” is here used in two different senses, on which see Whately’s Logic, Appendix, Art.  “Law.”] Ethics, however, must also consider the conditions under which what ought to happen frequently does not.

We may call all philosophy empirical, so far as it is based on grounds of experience:  on the other hand, that which delivers its doctrines from a priori principles alone we may call pure philosophy.  When the latter is merely formal it is logic; if it is restricted to definite objects of the understanding it is metaphysic.

In this way there arises the idea of a two-fold metaphysic—­a metaphysic of nature and a metaphysic of morals.  Physics will thus have an empirical and also a rational part.  It is the same with Ethics; but here the empirical part might have the special name of practical anthropology, the name morality being appropriated to the rational part.

All trades, arts, and handiworks have gained by division of labour, namely, when, instead of one man doing everything, each confines himself to a certain kind of work distinct from others in the treatment it requires, so as to be able to perform it With greater facility and. in the greatest perfection.  Where the different kinds of work are not so distinguished and divided, where everyone is a jack-of-all-trades, there manufactures remain still in the greatest barbarism.  It might deserve to be considered whether pure philosophy in all its parts does not require a man specially devoted to it, and whether it would not be better for the whole business of science if those who, to please the tastes of the public, are wont to blend the rational and empirical elements together, mixed in all sorts