In Prisons and Prison Discipline Mill applies his theory of education to penal reform. Just as one’s character can be well moulded by a good education, so too may one’s character be badly moulded through miseducation. The latter, Mill maintains, is especially evident in the criminal class. Criminals commit crimes and are sent to prison because they have been badly educated. Punishment, properly understood, is a kind of remedial education, and prison, properly structured, presents the opportunity to re-mould inmates’ misshapen characters. Prisons and Prison Discipline delineates the types of punishments likely to deter offenders or, failing that, to re-mould and re-educate criminals to be productive members of society. In these and other respects Mill’s theory of punishment mirrors Plato’s. Like Plato, Mill draws a sharp distinction between punishing someone and harming him. The purpose of punishment is to reform (literally re-form) the soul or character of the inmate so that he may be released into society without fear that he will harm others. But to harm someone is to make him worse, and an even greater danger to society (Ball 1995, ch. 7).