78 Now God Himself liberally sows in the generous hearts of many young men this precious seed of vocation; but human means of cultivating this seed must not be neglected. There are innumerable ways and countless holy means suggested by the Holy Spirit; and all such salutary works which strive to preserve, promote and help priestly vocations, We praise and bless with all Our heart. "No matter how we seek," says the lovable Saint of charity, Vincent de Paul, "we shall always discover ourselves unable to contribute to anything more great than to the making of good priests." In truth nothing is more acceptable to God, of more honor to the church, and more profitable to souls than the precious gift of a holy priest. If he who offers even a cup of water to one of the least of the disciples of Christ "shall not lose his reward," what reward will he receive who places, so to speak, into the pure hands of a young priest the sacred chalice, in which is contained the Blood of Redemption; who helps him to lift it up to heaven, a pledge of peace and of blessing for mankind?
Source: Ad Catholici Sacerdotii (Vatican.va)