essential illustrations seem to be most important to the unscientific mind; and this explains the unjust reproaches directed against science.
Only the scientific mind has the right to criticise the validity of knowledge. And whatever may be said against the validity of general scientific propositions, such as the laws of physics: it may be said with much greater right against all assertions in any other field of human occupation and life. The fundamental propositions rest on a much broader basis of experiment than any of the beliefs which are held most strongly in every day life. Under these circumstances nobody should speak disparagingly of the validity of scientific knowledge — not even the scientist himself.
If any philosopher should be disappointed by an analysis because we had to deny the possibility of real a priori knowledge, he will find enough compensation when we go on to examine the scope of knowledge instead of the validity. Most philosophers have stated with regret that human understanding, however efficiant it may be in some fields, is entirely incompetent in other fields, that the scope of knowledge is restricted to certain parts and aspects of the world, while other parts and aspects must forever remain beyond its reach. There are certain limits which it cannot possibly transcend. Beyond these limits there is the Unknowable into which our reason and our senses can never penetrate.
This view is held by schools of various descriptions: we find it among empiricists like Herbert Spencer, who believes in the existence of the Unknown beyond the realm of experience, this realm of experience is just a corner or section of the world to which all our knowledge is definitely confined. We find it also among rationalists who have the greatest faith in reason, like Spinoza — God in Nature, he says has an infinite number of attributes — but only two of these can be known to man, he has no conception of the infinite rest. We find it in the "critical" philosophy of Kant, who declares that human knowledge is restricted to phaenomena, appearances, while the things in themselves, of which they are the appearances are absolutely unapproachable, our reason as well as our senses live within unsurmoutable walls.
Now. I believe we shall all agree most heartily that we cannot know everything. I cannot tell you what the back side of the moon looks like, and it is even possible that no human being will ever know it. No historian knows,
