When a white man in Africa by accident looks into the eyes of a native and sees the human being (which it ishis chief preoccupation to avoid), his sense of guilt, which he denies, fumes up in resentment and he brings down the whip.

-Lessing, Doris May ne¤  e Tayler
  The Grass Is Singing, ch.8.

There is only one constant preoccupation: I have throughout been anxious to discover how much we can be said to know and with what degree of certainty or doubtfulness.

-Russell, Bertrand Arthur William Russell, 3rd Earl
  My Philosophical Development, ch.1.