"It is difficult to say
what is impossible,
for the dream of yesterday
is the hope of today and
the reality of tomorrow."
-- Dr. Robert H. Goddard
"There is no way back into the past;
the choice, as H. G. Wells once said,
is the universe -- or nothing.
Though men and civilizations
may yearn for rest, for the
dream of the lotus-eaters,
that is a desire that merges
imperceptibly into death.
The challenge of the great
spaces between the worlds
is a stupendous one; but
if we fail to meet it,
the story of our race will
be drawing to its close."
-- Arthur C. Clarke