19 He fixed deeply in his mind and scrupulously observed what the martyr Cyprian, the witness of the ancient tradition of the Church, affirmed: "there is one God and one Christ; There is one Church and one founded on Peter by the word of the Lord." That is what the great Doctor of the Church Ambrose also preached: "Where Peter is, there is the Church. Where the Church is, there is no death but life eternal." Finally Jerome very wisely taught: "The welfare of the Church depends on the dignity of the papacy. If we do not give the pope sovereign and independent power, there will be as many schisms in the Church as there are priests."
Source: In Hac Tanta (Vatican.va)