Everyone knows that dragons don't exist. But while this simplistic
formulation may satisfy the layman, it does not suffice for the scientific
mind. The School of Higher Neantical Nillity is in fact wholly unconcerned
with what does exist. Indeed, the banality of existence has been
so amply demonstrated, there is no need for us to discuss it any further
here. The brilliant Cerebron, attacking the problem analytically,
discovered three distinct kinds of dragon: the mythical, the chimerical,
and the purely hypothetical. They were all, one might say, nonexistent,
but each nonexisted in an entirely different way ...
- -- Stanislaw Lem, "Cyberiad"