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. And then there were the imaginary dragons, and the a-, anti- and minus-dragons (colloquially termed nots, noughts and oughtn'ts by the experts), the minuses being the most interesting on account of the well-known dracological paradox: when two minuses hypercontiguate (an operation in the algebra of dragons corresponding roughly to simple multiplication), the product is 0.6 dragon, a real nonplusser. Bitter controversy raged among the experts on the question of whether, as half of them claimed, this fractional beast began from the head down or, as the other half maintained, from the tail up.