7 Moreover, in this most admirable Sacrament, which is the chief means whereby men are engrafted on the divine nature, men also find the most efficacious help towards progress in every kind of virtue. And first of all in faith. In all ages faith has been attacked; for although it elevates the human mind by bestowing on it the knowledge of the highest truths, yet because, while it makes known the existence of divine mysteries, it yet leaves in obscurity the mode of their being, it is therefore thought to degrade the intellect. But whereas in past times particular articles of faith have been made by turns the object of attack; the seat of war has since been enlarged and extended, until it has come to this, that men deny altogether that there is anything above and beyond nature. Now nothing can be better adapted to promote a renewal of the strength and fervour of faith in the human mind than the mystery of the Eucharist, the "mystery of faith," as it has been most appropriately called. For in this one mystery the entire supernatural order, with all its wealth and variety of wonders, is in a manner summed up and contained: "He hath made a remembrance of His wonderful works, a merciful and gracious Lord; He bath given food to them that fear Him" (Psalm cx, 4-5). For whereas God has subordinated the whole supernatural order to the Incarnation of His Word, in virtue whereof salvation has been restored to the human race, according to those words of the Apostle; "He bath purposed...to re-establish all things in Christ, that are in heaven and on earth, in Him" (Eph. i., 9-10), the Eucharist, according to the testimony of the holy Fathers, should be regarded as in a manner a continuation and extension of the Incarnation. For in and by it the substance of the incarnate Word is united with individual men, and the supreme Sacrifice offered on Calvary is in a wondrous manner renewed, as was signified beforehand by Malachy in the words: "In every place there is sacrifice, and there is offered to My name a pure oblation" (Mal. i., II). And this miracle, itself the very greatest of its kind, is accompanied by innumerable other miracles; for here all the laws of nature are suspended; the whole substance of the bread and wine are changed into the Body and the Blood; the species of bread and wine are sustained by the divine power without the support of any underlying substance; the Body of Christ is present in many places at the same time, that is to say, wherever the Sacrament is consecrated. And in order that human reason may the more willingly pay its homage to this great mystery, there have not been wanting, as an aid to faith, certain prodigies wrought in His honour, both in ancient times and in our own, of which in more than one place there exist public and notable records and memorials. It is plain that by this Sacrament faith is fed, in it the mind finds its nourishment, the objections of rationalists are brought to naught, and abundant light is thrown on the supernatural order.
Source: Mirae Caritatis (Vatican.va)