We can judge our progress by the courage of our questions and the depth of our answers, our willingness to embrace what is true rather than what feels good.
Carl SaganFrederick Douglas taught that literacy is the path from slavery to freedom. There are many kinds of slavery and many kinds of freedom, but reading is still the path.
Carl SaganWhat does it mean for a civilisation to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical civilisation is a few hundred years old ... an advanced civilisation millions of years old is as much beyond us as we are beyond a bushbaby or a macaque
Carl SaganIndeed the reasoned criticism of a prevailing belief is a service to the proponents of that belief; if they are incapable of defending it, they are well advised to abandon it. This self-questioning and error-correcting aspect of the scientific method is its most striking property.
Carl Sagan