St. Irenaeus was a 2nd-century bishop who believed the Eucharist was the body and blood of Jesus Christ.
St. Irenaeus lived from about 130 - 202, and his writings provide an early witness to the Church's beliefs about the Eucharist.
He writes in his book Against Heresies that something extraordinary happens at Mass.
St. Irenaeus points out that the bread and wine experiences a transformation at Mass at the words of consecration, turning them into something new, both heavenly and earthly.
In a different part of his book he reveals what exactly they change into.
This is consistent with what the Catechism of the Catholic Church currently states.
St. Irenaeus was simply stating something the Church has never ceased to teach about the Eucharist: that the bread and wine become, through the power of God, the body and blood of Jesus Christ.
