Why does humankind still grapple with the greatest questions?  Why can we ultimately know nothing?  And what, then, shall we occupy ourselves with?  All is revealed here:

"I have always been interested in the oddities of mankind.  At one time I read a good deal of philosophy and a good deal of science, and I learned in that way that nothing was certain.  Some people, by the pursuit of science, are impressed with the dignity of man, but I was only made conscious of his insignificance.  The greatest questions of all have been threshed out since he acquired the beginnings of civilization and he is as far from a solution as ever.  Man can know nothing, for his senses are his only means of knowledge, and they can give no certainty.  There is only one subject upon which the individual can speak with authority, and that is his own mind, but even here is surrounded with darkness.  I believe that we shall always be ignorant of the matters which it most behoves us to know, and therefore I cannot occupy myself with them.  I prefer to set them all aside, and, since knowledge is unattainable, to occupy myself only with folly." —William Somerset Maugham, The Magician