"The greatest obstacle to pleasure is not pain; it is delusion. The principal enemies of human happiness are inordinate desire--the fantasy of attaining something that exceeds what the finite mortal world allows--and gnawing fear. Even the dreaded plague, in Lucretius' account--and his work ends with a graphic account of a catastrophic plague epidemic in Athens--is most horrible not only for the suffering and death that it brings but also and still more for the "perturbation and panic" that it triggers."