This need to discern more clearly what is contained in the deposit of faith given to the Church by the apostles points us to the related subjects of infallibility and inspiration. The pope and the bishops (when teaching in union with him) have the charism of infallibility when defining matters of faith or morals; but infallibility works only negatively. Through the intervention of the Holy Spirit, the pope and bishops are prevented from teaching what is untrue, but they are not forced or told by the Holy Spirit to teach what is true. To put it another way, the pope and the bishops are not inspired the way the authors of Scripture or the prophets were. To make a new definition, to clear up some dogmatic confusion, they first have to use human reason, operating on what is known to date, to be able to teach more precisely what is to be held as true. They cannot teach what they do not know, and they learn things the same way we do. They have no access to prophetic shortcuts—they must delve by study into the riches of the words God has already given us.