"And this food is called by us the Eucharist. Of which no one is allowed to partake but he who believes that the things which we teach are true, and who has been washed in the bath for the forgiveness of sins and to regeneration, and who so lives as Christ has directed. For not as ordinary bread and ordinary drink do we receive these, but in like manner as by the word of God Jesus Christ our Savior was made flesh and had both flesh and blood for our salvation, so also the food, which is blessed by the prayer of the Word which proceeded from him and from which our flesh and blood by transmutation are nourished, is, we are taught, the flesh and blood of that Jesus who was made flesh. For the apostles in the memoirs which they composed and which are called gospels have declared that they were commanded to do as follows: that Jesus took bread and gave thanks and said, 'this do in remembrance of me, this is my body', and in like manner he gave thanks and said 'this is my blood' and gave it to them alone (Apology, I, 62)."
- St. Justin, Martyr (cited in Quasten, Vol. I, 216)