"We should therefore never be too quick to dismiss any
cosmic locale as inhospitable -- worse yet, hostile --
to the presence of life.
"In our search for its existence, we must never underestimate
the determination, the dogged persistence, of living systems.
"Of course, we shall find nothing resembling life as we
know it. Our sample has been finely honed to fit the
specific requirements of the third planet from the Sun.
Every other potential environment will be equally unique.
"The succession of biological experiments posed by genetic
mutations will have different outcomes in different settings.
Since their occurance is pure happenstance anyway, their
outcome here on Earth could never be precisely repeated.
"Hence the diversity of Earthbound life about which we marvel
represents but a narrow slice of the total possible spectrum.
Perhaps a near-infinity of living creatures, some wilder than
we are capable of imagining, await our discovery -- or we theirs."
- George A. Seielstad, Chapter 6: "Other Worlds",
page 97, from Cosmic Ecology: The View from the Outside In,
University of California Press, Berkeley, 1983