It's like my granddaughter who fried my computer, last week. She didn't get what a computer is, how important it is--it's job, what it means to me. She touched it because she felt hurt that I said she couldn't.
I was reminded of this when I read the Second Reading, in the Office of Readings, for the Third Sunday of Easter. Saint Justin, martyr (Cap. 66-67: PG 6, 427-431) in talking about the celebration of the Eucharist:
No one may share the Eucharist with us unless he believes that what we teach is true, unless he is washed in the regenerating waters of baptism for the remission of his sins, and unless he lives in accordance with the principles given us by Christ.
We do not consume the Eucharistic bread and wine as if it were ordinary food and drink, for we have been taught that as Jesus Christ our Savior became a man of flesh and blood by the power of the Word of God, so also the food that our flesh and blood assimilates for its nourishment becomes the flesh and blood of the incarnate Jesus by the power of his own words contained in the prayer of thanksgiving.
The apostles, in their recollections, which are called gospels, handed down to us what Jesus commanded them to do. They tell us that he took bread, gave thanks and said: Do this in memory of me. This is my body. In the same way he took the cup, he gave thanks and said: This is my blood. The Lord gave this command to them alone. Ever since then we have constantly reminded one another of these things.
As you read, the Church has always taught this. It is not a new idea, or fancy of priests. It has always been so.