Carl%20Sagan%20-%20The%20Demon%20Haunted%20World

The Wind Makes Dust
theologians are highly skilled in their intricate and arcane arts.
No, the impediment is political and hierarchical. In those cultures
lacking unfamiliar challenges, external or internal, where fundamental
change is unneeded, novel ideas need not be encouraged.
Indeed, heresies can be declared dangerous; thinking can be
rigidified; and sanctions against impermissible ideas can be
enforced - all without much harm. But under varied and changing
environmental or biological or political circumstances, simply
copying the old ways no longer works. Then, a premium awaits
those who, instead of blandly following tradition, or trying to foist
their preferences on to the physical or social Universe, are open to
what the Universe teaches. Each society must decide where in the
continuum between openness and rigidity safety lies.
Greek mathematics was a brilliant step forward. Greek science,
on the other hand - its first steps rudimentary and often uninformed
by experiment - was riddled with error. Despite the fact
that we cannot see in pitch darkness, they believed that vision
depends on a kind of radar that emanates from the eye, bounces
off what we're seeing, and returns to the eye. (Nevertheless, they
made substantial progress in optics.) Despite the obvious resemblance
of children to their mothers, they believed that heredity
was carried by semen alone, the woman a mere passive receptacle.
They believed that the horizontal motion of a thrown rock
somehow lifts it up, so that it takes longer to reach the ground
than a rock dropped from the same height at the same moment.
Enamoured of simple geometry, they believed the circle to be
'perfect'; despite the 'Man in the Moon' and sunspots (occasionally
visible to the naked eye at sunset), they held the heavens also
to be 'perfect'; therefore, planetary orbits had to be circular.
Being freed from superstition isn't enough for science to
grow. One must also have the idea of interrogating Nature, of
doing experiments. There were some brilliant examples -
Eratosthenes's measurement of the Earth's diameter, say, or
Empedocles's clepsydra experiment demonstrating the material
nature of air. But in a society in which manual labour is
demeaned and thought fit only for slaves, as in the classical
Graeco-Roman world, the experimental method does not
thrive. Science requires us to be freed of gross superstition and
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