For lust of knowing what should not be known, We take the Golden Road to Samarkand.

-Flecker,James Elroy
  'The Golden  Journey to Samarkand', epilogue.

Furnished as all Europe is with Academies of Science, with nice instruments and the spirit of experimentation, the progress of human knowledge will be rapid and discoveries made of which we have at present no conception. I begin to be almost sorry I was born since I cannot have the happiness of knowing what will be known a hundred years hence.

-Frank, Anne
  Letter to Sir  Joseph Banks, President of the Royal Society, 27  Jul.

As the art of reading (after a certain stage in one's education) isthe art of skipping, so the art of being wise is the art of knowing what to overlook.

-James,William
  The Principles of Psychology, ch.22.

Eben darin Philosophie besteht, seine Grenzen zu kennen. It is precisely in knowing its limits that philosophy consists.

-Kant, Immanuel
Kritik der reinen Vernunft (Critique of Pure Reason), B755 (translated by N Kemp Smith).

Mary lived by wondering what lay round the corner. I lived by knowing there was no corner.

-Kavanagh, P(atrick) J(oseph Gregory)
  A Happy Man, ch.12.

   Part of knowing who we are is knowing we are not someone else. And Jew is only the name we give to that stranger, the agony we cannot feel, the death we look at like a cold abstraction. Each man has his Jew; it is the other.

-Miller, Arthur
  Leduc. Incident at Vichy, act1.