2 For this John, dearly beloved brethren, was one of those mountains concerning which it is written: “Let the mountains receive peace for your people, and the hills righteousness.” The mountains are lofty souls, the hills little souls. But for this reason do the mountains receive peace, that the hills may be able to receive righteousness. What is the righteousness which the hills receive? Faith, for “the just does live by faith.” The smaller souls, however, would not receive faith unless the greater souls, which are called mountains, were illuminated by Wisdom herself, that they may be able to transmit to the little ones what the little ones can receive; and the hills live by faith, because the mountains receive peace. By the mountains themselves it was said to the Church, “Peace be with you;” and the mountains themselves in proclaiming peace to the Church did not divide themselves against Him from whom they received peace, that truly, not feignedly, they might proclaim peace.
Source: Tractates on the Gospel of John (New Advent)