Again, if the name _Theory of Knowledge_ is understood, as it sometimes has been, to suggest that it is possible to study the nature and capabilities of the knowing faculty apart from the study of the contents of knowledge, it becomes a source of positive and dangerous mistake. The capabilities and limitations of the knowing faculty can only be ascertained by inquiring into the truth of its knowledge, regarded as an apprehension of reality; there is no possible way of severing the faculty, as it were, by abstraction from the results of its exercise, and examining its structure, as we might that of a mechanical appliance, before investigating the value of its achievements. The instrument can only be studied in its work, and we have to judge of its possibilities by the nature of its products. It is therefore advisable to indicate, by our choice of a name for our subject, that the theory of Knowing is necessarily also a theory of Being. _Consult further_:—F. H. Bradley, _Appearance and Reality_, Introduction; L. T. Hobhouse, _The Theory of Knowledge_, Introduction; H. Lotze, _Metaphysic_, Introduction (Eng. trans., vol. i. pp. 1-30) ----- Footnote 1: The name simply means “what comes after Physics,” and probably owes its origin to the fact that early editors of Aristotle placed his writings on ultimate philosophical questions immediately after his physical treatises. Footnote 2: For an example of these puzzles, compare the passage (_Republic_, 524) where Plato refers to cases in which an apparent contradiction in our sensations is corrected by _counting_. Footnote 3: Of course we must not assume that “_every_ appearance is _only_ appearance,” or that “nothing is both reality and appearance.” This is just the uncritical kind of preconception which it is the business of Metaphysics to test. Whether “every appearance is only appearance” is a point we shall have to discuss later. Footnote 4: Cf. F. H. Bradley, _Appearance and Reality_, pp. 1-4. Footnote 5: I may be pardoned for reminding the reader who may be new to our subject, that “facts” and “processes” are only properly called _phenomena_ when it is intended to imply that as they stand they are _not_ genuine realities but only the partially misleading appearance of reality which is non-phenomenal or ultra-phenomenal. (We shall do well to avoid the pretentious error of calling the ultra-phenomenal, _as such_, “_noumenal_.”) Footnote 6: _Appearance and Reality_, chap. 12, p. 129 (ed. 1). Footnote 7: As, for instance, all mental states are, according to certain psychologists, non-quantitative. Footnote 8: The student will find Höffding’s _History of Modern Philosophy_ (English translation in 2 vols., Macmillan) particularly valuable for the way in which the author brings out the intimate historical connection between the development of Metaphysics and the general progress of science. Footnote 9: