Ah! "Ability or inability to conceive," says Mr. Mill, very properly, "is in no case, to be received as a criterion of axiomatic truth." What modern in his senses would ever think of disputing this truism? The only wonder with us must be, how it happened that Mr. Mill conceived it necessary even to hint at anything so obvious. So far, good--but let us turn over another paper. What have we here? "Contradictories cannot both be true--that is, cannot coexist in nature." Here Mr. Mill means, for example, that a tree must be either a tree or not a tree--that it cannot be at the same time a tree and not a tree. Very well; but I ask him why. His reply is this--and never pretends to be anything else than this--"Because it is impossible to conceive that contradictories can both be true." But this is no answer at all, by his own showing; for has he not just admitted as a truism that "ability or inability to conceive is in no case to be received as a criterion of axiomatic truth"? Now I do not complain of these ancients so much because their logic is, by their own showing, utterly baseless, worthless and fantastic altogether, as because of their pompous and imbecile proscription of all other roads of Truth, of all other means for its attainment than the two preposterous paths--the one creeping and the one of crawling--to which they have dared to confine the Soul that loves nothing so well as to soar. By the by, my friend, do you not think it would have puzzled these ancient dogmaticians to have determined by which of their two roads it was that the most important and most sublime of all their truths was, in effect, attained? I mean the truth of Gravitation. Newton owed it to Kepler. Kepler admitted that his three laws were guessed at--these three laws of all laws which led the great Inglitch mathematician to his principle, the basis of all physical principle--to go behind which we must enter the Kingdom of Metaphysics: Kepler guessed--that is to say, imagined. He was essentially a "theorist"--that word now of so much sanctity, formerly an epithet of contempt. Would it not have puzzled these old moles, too, to have explained by which of the two "roads" a cryptographist unriddles a cryptograph of more than usual secrecy, or by which of the two roads Champollion directed mankind to those enduring and almost innumerable truths which resulted from his deciphering the Hieroglyphics?