The usual rejoinder to someone who says 'They laughed at Columbus, they laughed at Galileo' is to say 'But they also laughed at Bozo the Clown'.
Carl SaganNot all birds can fly. What separates the flyers from the walkers is the ability to take off.
Carl SaganPerhaps, in retrospect, there would be little motivation even for malevolent extraterrestrials to attack the Earth; perhaps, after a preliminary survey, they might decide it is more expedient just to be patient for a little while and wait for us to self-destruct.
Carl SaganBetter by far to embrace the hard truth than a reassuring fable. If we crave some cosmic purpose, then let us find ourselves a worthy goal.
Carl Sagan