have arrived at essentially the same point of view. These philosophers maintain the Relativity of our knowledge in the most extreme form in which the doctrine can be understood, since they contend, not merely that all we can possibly know of anything is the manner in which it affects the human faculties, but that there is nothing else to be known; that affections of human or of some other minds are all that we can know to exist." Mr. Mill's own position will be found in his 11th Chapter. After defining Matter to be a "Permanent Possibility of Sensation," (p. 227) and explaining his definition, he writes in a note (p. 232), the following decisive sentences: "My able American critic, Dr. H. B. Smith, contends through several pages that these facts afford no proofs that objects _are_ external to us. I never pretended that they do. I am accounting for our conceiving, or representing to ourselves, the Permanent Possibilities as real objects external to us. I do not believe that the real externality to us of anything, except other minds, is capable of proof." Mr. O'Hanlon's pamphlet entitled "A Criticism of John Stuart Mill's Pure Idealism; and an attempt to shew that, if logically carried out, it is Pure Nihilism," seems less known than it deserves to be. Mr. Mill noticed and answered it in his 3rd Edition--chiefly among the criticisms commencing p. 244.----Mr. O'Hanlon's early decease has given a painful interest to his promising labours. Some paragraphs from his now scarce pamphlet are placed at the end of Additional Note D, on "Pure Idealism." [105] _On Hamilton._ p. 6. Mill is thus echoed from across the broad Atlantic;--"The profoundest question of philosophy turns on the relation of Thought to Being, Mind to Matter, Subject to Object, or (in empiricistic phrase) Organism to Environment. Is the Organism purely the product of the Environment? Then we have Empiricism, Sensationalism, Materialism, whose motto is that of Destutt-Tracy,--"_Penser c'est sentir_." Is the Environment the product of the Organism? Then we have Transcendentalism, Egoism, Idealism, whose motto is that of Berkeley,--"The _esse_ of objects is _percipi_." F. E. Abbot, in _The Index_ (American), for July 27, 1872.