It has been, and _is_ to be, objected, that logic, thus confined, 'leaves untouched the greatest difficulties, and those which are the sources of the greatest errors in reasoning.' To this powerful objection Dr. Whately thinks it sufficient to reply, that 'no art is to be censured for not teaching more than falls within its province, and, indeed, more than can be taught by any conceivable art. Such a system of universal knowledge as should instruct us in the full meaning or meanings of every term, and the truth or falsity, certainty or uncertainty of every proposition, thus superseding all other studies, it is most unphilosophical to expect, or even to imagine. And to find fault with logic for not performing this, is as if one should object to optics for not giving sight to the blind--or complain of a reading glass for being of no service to a person who had never learnt to read.'*** This would be a most conclusive answer if confident assertion could be accepted in lieu of proof. The objection still remains to be removed. We may still demand, does it not fall within the legitimate province of logic to provide means of encountering the 'greatest difficulties' with which it is confessed logic is beset? True, there is no art can teach everything, but is that a reason why logic should teach nothing, or next to nothing, compared with what seems essentially necessary? * Intro., p. 1. ** Klein. of Logic, Synthetical Compendium, chap. 2, part 1, sec. 9. *** Elem. of Logic, Intro., pp. 12, 13. Dr. Whately contends that the 'difficulties' and 'errors' in the objection adduced, are in the _subject matter_ about which logic is employed, and _not_ in the process of reasoning--which alone is the appropriate province of logic. But it seems to me that Dr. Whately has found it impossible to keep within the bounds of the restriction he thus endeavours to establish. In treating upon 'apprehension,' he introduces, as indeed he was obliged to do, from the department of metaphysics, several speculations on 'generalisation' and 'abstractions,' and from ontology (the science which explains the most general conceptions respecting the phenomena of nature) he borrows the leading principles of definition. Because he thus goes so far, it is not to be contended that _therefore_ he should have gone further; but when he found he must depart from his rule and borrow from other branches of knowledge (no matter for what end), why did he not depart from it to some purpose, and borrow from natural philosophy such rules as would have guarded the logician from the 'chief errors' into which he may fall?