offered, he stated the premises, whether principal or secondary, and the conclusions of Paul's arguments in accordance with the rules of Logic".

As a result of his growing reputation Lanfranc was invited to defend the doctrine of transubstantiation against the attacks of Berengar of Tours. He took up the task with the greatest zeal, although Berengar had been his personal friend; he was the protagonist of orthodoxy at the Church Councils of Vercelli