What is objectionable, what is dangerous, about extremists is not that they are extreme, but that they are intolerant. The evil is not what they say about their cause, but what they say about their opponents.
The great liability of the engineer compared to men of other professions is that his works are out in the open where all can see them. His acts, step by step, are in hard substance. He cannot bury his mistakes in the grave like the doctors. He cannot argue them into thin air or blame the judge like the lawyers. He cannot, like the architects, cover his failures with trees and vines. He cannot, like the politicians, screen his sort-comings by blaming his opponents and hope the people will forget. The engineer simply cannot deny he did it. If his works do not work, he is damned.
Souls are like athletes, that need opponents worthy of them, if they are to be tried and extended and pushed to the full use of their powers, and rewarded according to their capacity.
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
When men are brought face to face with their opponents, forced to listen and learn and mend their ideas, they cease to be children and savages and begin to live like civilized men. Then only is freedom a reality, when men may voice their opinions because they must examine their opinions.
I have always felt that a politician is to be judged by the animosities he excites among his opponents.
At times one remains faithful to a cause only because its opponents do not cease to be insipid.