Pessimists are just as illogical as optimists; insomuch as both envisage the aims of mankind as unified, and as having a direct relationship (either of frustration or of fulfilment) to the inevitable flow of terrestrial motivation and events. That is--both schools retain in a vestigial way the primitive concept of a conscious teleology--of a cosmos which gives a damn one way or the other about the especial wants and ultimate welfare of mosquitos, rats, lice, dogs, men, horses, pterodactyls, trees, fungi, dodos, or other forms of biological energy.