_Analysis_--Man the interpreter of Nature. Nature _gives_ by answering our interrogations; these must depend on our powers of assimilating knowledge. Some questions inevitable, _e.g._, What are the first grounds of Truth? Has Man any faculty of apprehending the Infinite? Can we know our own Personality or that of others?--or any Thing in itself? Inference against Scepticism based on human ignorance. Fallacy of the Unthinkable or Inconceivable. Ideas of Self and not-Self, inexplicable, yet undoubted. From things as they are, let us turn to things as they appear. How do we perceive, hear, see? Perception as an instrument of Intelligence, inscrutable. We acknowledge the insoluble mystery but accept the fact. Marvels of eyesight, and their problems. How much and what do we see? Comparison with Sound;--Form, Colour, Tone. Evidence on which we receive sense impressions. Comparison between healthy and diseased sensations,--between our organs of sense and those of animals. We soon arrive at a twilight territory of knowledge and can explain no more. Imperfections in our powers of Verification. How great is the subjective Element in our perceptions? Idealism,--most difficult to answer when most extreme. Philosophic denial of all proof of external things as distinguished from Mind (_e.g._, by Mill). Fact-knowledge, and absurdities involved in the ordinary method of defining and alleging Facts. Polar tendencies of Phenomenalism which take the shapes of Idealism and Positivism, resulting in Nihilism or Indifferentism. The end of these things! Mr. Herbert Spencer on Theology, compared with Mr. Huxley, and criticized by Mr. J. Martineau, who denies that the Unknowable can be any object of religious feeling,--a protest strongly maintained by Mr. J. S. Mill. The difficulties attending every kind of knowledge paralleled with the difficulties alleged against Theism. If the Inexplicable be also the Unknowable, there is an end to all knowledge. We cannot predicate veracity of our human Mind, we cannot even know that we know anything. Mr. J. S. Mill accepts Mind as an inexplicable Fact underlying all other Facts and Beliefs. We _must_ accept _ultimate_ Truths. Transition to Chapter IV. on the affirmative evidence for our Reasonable Beliefs. Corollary on Materialism. Far more difficult than its antithesis. Conclusion to be drawn from these difficulties. _Additional Notes and Illustrations._ A.--Account of some theories respecting our Personal Identity. B.--Helmholtz, Popular Lectures on Recent Progress of the Theory of Vision. C.--Helmholtz on Specialties of Sensibility. D.--Popular account of Pure Idealism with critical remarks. E.--On the Relations of Fact and Theory. F.--On the "Unknowable." G.--Mr. J. S. Mill as an Independent Moralist. _Additions to Corollary._ Note H.--Archebiosis, or Spontaneous Generation. I.--On Materialism. CHAPTER III. CONDITIONS OF HUMAN KNOWLEDGE.