We may henceforth consider ourselves face to face with Sphinx; and it is well to take the true measure of her lineaments. If the above reasoning be sound, to know, is to make a mirror and reflect ourselves back from it. To verify, is to put ourselves in new postures before our infallible mirror. Each fresh item of induction, is a freshly reflected phantom. At all events, the contrary position will never be established. Ignorant as we are, respecting the true centre of our mental firmament, we must necessarily be always more ignorant respecting all _possibilities_ which seemingly outlie its glowing horizon. No one who rationally weighs the worth of a fact, or who decomposes it into its elementary constituents, will ever be absurd enough to imagine that he can disprove the ideal theory by proving the truth of its opposite. The strongest strain of Idealism comes upon the _last_ sentence. Some years ago, English philosophers had agreed in the conclusion that all debates must for the future be settled by an appeal to facts. Could there be a more happily chosen ground for arbitration?--or one better suited to the calibre of everybody concerning whose business-like reflections we might say, with King Henry,-- "His thinkings are below the moon"? Some inquiring spirits preferred "law," but then they agreed with all others, (except transcendentalists,) that a law to be valid must also be a fact. A belief in this settlement still pervades most non-philosophic circles. A fact is now-a-days an infallible remedy for the disturbed mind; just as once "the sovereign'st thing on earth Was parmaceti for an inward bruise." A mind too disturbed to abstain from logical litigation when this receipt is administered, must certainly be afflicted with monomania. Nobody, of course, (whether Idealist or Transcendentalist,) need feel much aggrieved by being called mad. At some time or other, it is the common lot of all, from a murderer proud of being caught red-handed in our day, to a Jewish Pharisee and the son of a Pharisee, long ago departed to his rest. Besides, some madnesses are so fortunate as to justify themselves, an event now happening to Idealists.[104] In Germany, France and England, the persuasion gains ground that no tasks are so difficult as first to define, and secondly to establish a fact. Now the task of a Natural Theologian, is to establish, (if he can), the greatest and most solemn of all facts. In order to do his work honestly, he must ascertain as far as possible the conditions of proof, the ground on which fact-knowledge reposes. And it will be admitted that the problem of evidence raised by Idealism, is difficult, crucial, and underlies all other problems. "The most fundamental questions in philosophy," says Mr. Mill, "are those which seek to determine what we are able to know of external objects, and by what evidence we know it."[105]