The modern and highly convenient term 'Agnosticism,' is used in two very different senses. By its originator, Professor Huxley, it was coined to signify an attitude of reasoned ignorance touching everything that lies beyond the sphere of sense-perception--a professed inability to found valid belief on any other basis. It is in this its original sense--and also, in my opinion, its only philosophically justifiable sense--that I shall understand the term. But the other, and perhaps more popular sense in which the word is now employed, is as the correlative of Mr. H. Spencer's doctrine of the Unknowable. This latter term is philosophically erroneous, implying important negative knowledge that if there be a God we know this much about Him--that He _cannot_ reveal Himself to man[39]. _Pure_ agnosticism is as defined by Huxley. Of all the many scientific men whom I have known, the most pure in his agnosticism--not only in profession but in spirit and conduct--was Darwin. (What he says in his autobiography about Christianity[40] shows no profundity of thought in the direction of philosophy or religion. His mind was too purely inductive for this. But, on this very account, it is the more remarkable that his rejection of Christianity was due, not to any _a priori_ bias against the creed on grounds of reason as absurd, but solely on the ground of an apparent moral objection _a posteriori_[41].) Faraday and many other first-rate originators in science were like Darwin. As an illustration of impure agnosticism take Hume's _a priori_ argument against miracles, leading on to the analogous case of the attitude of scientific men towards modern spiritualism. Notwithstanding that they have the close analogy of mesmerism as an object-lesson to warn them, scientific men as a class are here quite as dogmatic as the straightest sect of theologians. I may give examples which can cause no offence, inasmuch as the men in question have themselves made the facts public, viz. ---- refusing to go to [a famous spiritualist]; ---- refusing to try ---- in thought-reading[42]. These men all _professed_ to be agnostics at the very time when thus so egregiously violating their philosophy by their conduct.