I think the discomfort that some people feel in going to the monkey cages at the zoo is a warning sign.
Carl SaganWe are at a crossroads in human history. Never before has there been a moment so simultaneously perilous and promising. We are the first species to have taken evolution into our own hands.
Carl SaganScientists make mistakes. Accordingly, it is the job of the scientist to recognize our weakness, to examine the widest range of opinions, to be ruthlessly self-critical. Science is a collective enterprise with the error-correction machinery often running smoothly.
Carl Sagan