From the beginning of the Holy Apostolic Catholic Church, the Eucharist is the central purpose of worship. Why? Dave, explains the meaning behind it.
The Didache(c. 90 A.D.)
But concerning the Eucharist, after this fashion give ye thanks.
First, concerning the cup. We thank thee, our Father, for the holy vine, David thy Son, which thou hast made known unto us through Jesus Christ thy Son; to thee be the glory for ever.
And concerning the broken bread. We thank thee, our Father, for the life and knowledge which thou hast made known unto us through Jesus thy Son; to thee be the glory for ever.
As this broken bread was once scattered on the mountains, and after it had been brought together became one, so may thy Church be gathered together from the ends of the earth unto thy kingdom; for thine is the glory, and the power, through Jesus Christ, for ever.
And let none eat or drink of your Eucharist but such as have been baptized into the name of the Lord, for of a truth the Lord hath said concerning this, Give not that which is holy unto dogs. ( 9:1-5)
On the Lord's Day of the Lord gather together, break bread and give thanks, after confessing your transgressions SO THAT YOUR SACRIFICE MAY BE PURE. Let no one who has a quarrel with his neighbor join you until he is reconciled by the Lord: "In every place and time let there be OFFERED TO ME A CLEAN SACRIFICE. For I am Great King," says the Lord, "and My name is wonderful among the Gentiles." (14:1-2)
St. Ignatius of Antioch (c. 110 A.D.)
I have no taste for corruptible food nor for the pleasures of this life. I desire the Bread of God, WHICH IS THE FLESH OF JESUS CHRIST, who was of the seed of David; and for drink I DESIRE HIS BLOOD, which is love incorruptible. (Letter to the Romans 7:3)
Take care, then, to use one Eucharist, so that whatever you do, you do according to God: FOR THERE IS ONE FLESH OF OUR LORD JESUS CHRIST, and one cup IN THE UNION OF HIS BLOOD; one ALTAR, as there is one bishop with the presbytery… (Letter to the Philadelphians 4:1)
They [i.e. the Gnostics] abstain from the Eucharist and from prayer, because they do not confess that THE EUCHARIST IS THE FLESH OF OUR SAVIOR JESUS CHRIST, flesh which suffered for our sins and which the Father, in his goodness, raised up again. (Letter to Smyrnians 7:1)
St. Justin the Martyr (c. 100 - 165 A.D.)
We call this food Eucharist; and no one else is permitted to partake of it, except one who believes our teaching to be true and who has been washed in the washing which is for the remission of sins and for regeneration [Baptism], and is thereby living as Christ has enjoined.
For not as common bread nor common drink do we receive these; but since Jesus Christ our Savior was made incarnate by the word of God and had both flesh and blood for our salvation, so too, as we have been taught, the food which has been made into the Eucharist by the Eucharistic prayer set down by Him, AND BY THE CHANGE OF WHICH our blood and flesh is nourished, IS BOTH THE FLESH AND THE BLOOD OF THAT INCARNATED JESUS. (First Apology, 66)
Moreover, as I said before, concerning the sacrifices which you at that time offered, God speaks through Malachi [1:10-12]…It is of the SACRIFICES OFFERED TO HIM IN EVERY PLACE BY US, the Gentiles, that is, OF THE BREAD OF THE EUCHARIST AND LIKEWISE OF THE CUP OF THE EUCHARIST, that He speaks at that time; and He says that we glorify His name, while you profane it. (Dialogue with Trypho, 41)