drugs, tattoos and piercings. The Church also warns against the opposite behavior of "excessive preoccupation with the health and welfare of the body that 'idolizes' physical perfection, fitness, and success at sports." Kidnapping, terrorism, and torture are forbidden, as well as sterilizations, amputations and mutilations that are not for therapeutic medical reasons. According to the Catechism, societies have a moral obligation to strive to provide healthy living conditions for all people. Church belief in the resurrection of the body led to a prohibition against cremation that was pastorally modified at the Second Vatican Council in the 1960s under limited circumstances, but those conditions have been largely ignored even by the clergy. According to the Catechism, burial of the dead is a corporal work of mercy that must treat the body with respect and love (e.g. scattering of cremated remains, burial in an unmarked grave, etc. are forbidden in the Catholic Church). Organ donation after death and organ transplants under certain terms, also autopsies for legal and scientific reasons are permitted. War and self-defense In the Sermon on the Mount, Jesus recalls the commandment, "You shall not kill" and then adds to it the proscriptions against anger, hatred and vengeance. Going further, Christ asks his disciples to love their enemies. The Catechism asserts that "it is legitimate to insist on respect for one's own right to life." Kreeft says, "self-defense is legitimate for the same reason suicide is not: because one's own life is a gift from God, a treasure we are responsible for preserving and defending." The Catechism teaches that "someone who defends his life is not guilty of murder even if he is forced to deal his aggressor a lethal blow." Legitimate defense can be not only a right but a grave duty for one who is responsible for the lives of others. The defense of the common good requires that an unjust aggressor be rendered unable to cause harm. For this reason, those who legitimately hold authority also have the right to use arms to repel aggressors against the civil community entrusted to their responsibility. The Church requires all to pray and work to prevent unjust wars, but allows for just wars if certain conditions are met: The reasons for going to war are defensive. "The damage inflicted by the aggressor ... must be lasting, grave, and certain." It is a last resort taken only after all other