This post is an excerpt from the Catechism of the Council of Trent. The online version of the Catechism can be found here.
The Effects of the Eucharist
But with regard to the admirable virtue and fruits of this Sacrament, there is no class of the faithful to whom a knowledge of them is not most necessary. For all that has been said at such length on this Sacrament has principally for its object, to make the faithful sensible of the advantages of the Eucharist. As, however, no language can convey an adequate idea of its utility and fruits, pastors must be content to treat of one or two points, in order to show what an abundance and profusion of all goods are contained in those sacred mysteries.
The Eucharist Gives Grace
If, then, grace and truth came by Jesus Christ, they must surely be poured into the soul which receives with purity and holiness Him who said of Himself: He that eateth my flesh and drinketh my blood abideth in me and I in him. Those who receive this Sacrament piously and fervently must, beyond all doubt, so receive the Son of God into their souls as to be ingrafted as living members on His body. For it is written: He that eateth me, the same also shall live by me; also: The bread which I will give is my flesh for the life of the world. Explaining this passage, St. Cyril says: The Word of God, uniting Himself to His own flesh, imparted to it a vivifying power: it became Him, therefore, to unite Himself to our bodies in a wonderful manner, through His sacred flesh and precious blood, which we receive in the bread and wine, consecrated by His vivifying benediction.
The Grace Of The Eucharist Sustains
When it is said that the Eucharist imparts grace, pastors must admonish that this does not mean that the state of grace is not required for a profitable reception of this Sacrament. For as natural food can be of no use to the dead, so in like manner the sacred mysteries can evidently be of no avail to a soul which lives not by the spirit. Hence this Sacrament has been instituted under the forms of bread and wine to signify that the object of its institution is not to recall the soul to life, but to preserve its life.
The reason, then, for saying that this Sacrament imparts grace, is that even the first grace, with which all should be clothed before they presume to approach the Holy Eucharist, lest they eat and drink judgment to themselves,’ is given to none unless they receive in wish and desire this very Sacrament. For the Eucharist is the end of all the Sacraments, and the symbol of unity and brotherhood in the Church, outside which none can attain grace.
The Eucharist Remits Venial Sins
It cannot be doubted that by the Eucharist are remitted and pardoned lighter sins, commonly called venial. Whatever the soul has lost through the fire of passion, by falling into some slight offence, all this the Eucharist, cancelling those lesser faults, repairs, in the same way, not to depart from the illustration already adduced as natural food, gradually restores and repairs the daily waste caused by the force of the vital heat within us. Justly, therefore, has St. Ambrose said of this heavenly Sacrament: That daily bread is taken as a remedy for daily infirmity. But these things are to be understood of those sins for which no actual affection is retained.
The Eucharist Strengthens Against Temptation
There is, furthermore, such a power in the sacred mysteries as to preserve us pure and unsullied from sin, keep us safe from the assaults of temptation, and, as by some heavenly medicine, prepare the soul against the easy approach and infection of virulent and deadly disease. Hence, as St. Cyprian records, when the faithful were formerly hurried in multitudes by tyrants to torments and death, because they confessed the name of Christ, it was an ancient usage in the Catholic Church to give them, by the hands of the Bishop, the Sacrament of the body and blood of our Lord, lest perhaps overcome by the severity of their sufferings, they should fail in the fight for salvation.
It also restrains and represses the lusts of the flesh, for while it inflames the soul more ardently with the fire of charity, it of necessity extinguishes the ardour of concupiscence.
The Eucharist Facilitates The Attainment Of Eternal Life
Finally, to comprise all the advantages and blessings of this Sacrament in one word, it must be taught that the Holy Eucharist is most efficacious towards the attainment of eternal glory. For it is written: He that eateth my flesh, and drinketh my blood, hath everlasting life, and I will raise him up on the last day. That is to say, by the grace of this Sacrament men enjoy the greatest peace and tranquillity of conscience during the present life; and, when the hour of departing from this world shall have arrived, like Elias, who in the strength of the bread baked on the hearth, walked to Horeb, the mount of God, they, too, invigorated by the strengthening influence of this (heavenly food), will ascend to unfading glory and bliss.
tradcatmaria 