"Quod itaque Redemptoris nostri conspicuum fuit, in sacramenta transivit; et ut fides excellentior esset ac firmior, visioni doctrina successit, cujus auctoritatem supernis illuminata radiis credentium corda sequerentur."
St. Leo the Great, Sermo 74.2 (Sermon no. 2 on the Ascension), as quoted at CCC 1115, but with "sacraments" substituted for "mysteries". CCSL 138; PL 54, col. 398A. NPNF, ser. 2, vol. 12, trans. Feltoe:
In order, therefore, dearly-beloved, that we may be capable of this blessedness [promised to those 'who have not seen and yet have believed'], when all things were fulfilled which concerned the Gospel preaching and the mysteries of the New Testament, our Lord Jesus Christ, on the fortieth day after the Resurrection in the presence of the disciples, was raised into heaven, and terminated His presence with us in the body, to abide on the Father’s right hand until the times Divinely fore-ordained for multiplying the sons of the Church are accomplished, and He comes to judge the living and the dead in the same flesh in which He ascended. And so that which till then was visible of our Redeemer was changed into a sacramental presence, and that faith might be more excellent and stronger, sight gave way to doctrine, the authority of which was to be accepted by believing hearts enlightened with rays from above.