Every probability - and most of our common, working beliefs are probabilities - is provided with buffers at both ends, which break the force of opposite opinions clashing against it; but scientific certainty has no spring in it, no courtesy, no possibility of yielding. All this must react on the minds which handle these forms of truth.

The Autocrat of the Breakfast-Table, Chapter III (p. 56), Houghton Mifflin Company. 1891