Instead of entertaining visions of a final victory of reason over magic and ignorance, we have to reconcile ourselves to the fact that the norms and ideals which permit the advancement of knowledge have to be defended in every generation against new enemies, who reappear like the heads of the Hydra as soon as others are decapitated, and who employ ever-new labels, catchwords and slogans to play on the perennial weaknesses of mankind. Whatever happens in the instrumental exact sciences, we can be sure that in matters where intellectual and moral considerations mesh, the struggle between the forces of light and the forces of darkness will never end.