<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Transubstantiation (in Latin, transsubstantiatio, in Greek μετουσίωσις metousiosis) is, according to the teachings of the Catholic Church, the change of substance by which the bread and wine offered in the sacrifice of the sacrament of the Eucharist during the Mass, become, in reality, the body and blood of Jesus . </P> <P> The Catholic Church teaches that the substance, or essence, of the Eucharistic offering is changed into both the body and blood of Christ . Belief in this doctrine was made obligatory by the Fourth Council of the Lateran in 1215, and was later challenged by various 15th century reformers--John Wycliffe in particular . </P>

When does the bread and wine become the body and blood