Ideas about the scope and meaning of freedom of speech do expand and contract with the times. At the moment, we live in an age that is very permissive, both legally and socially, on a wide range of subjects from Karl Marx to kinky sex. This has not always been the case. Things that even children freely see and read and hear today -- writings, pictures, words -- would have been banned as just plain obscene, even for adults, as recently as the middle of the twentieth century.