It is discouraging to talk with men who will recognize no principles. How little use is made of reason in this world! You argue with a man for an hour, he agrees with you step by step, you are approaching a triumphant conclusion, you think that you have converted him; but ah, no, he has a habit, he takes a pinch of snuff, he remembers that he entertained a different opinion at the commencement of the controversy, and his reverence for the past compels him to reiterate it now.

Thoreau, Henry David. The Journal of Henry David Thoreau, 1837-1861.