When the Protestant Reformers began to deny the "whatness" of the Eucharist, the Catholic Church decided to pick up Thomas Aquinas' idea of Transubstantiation. This defined what the Eucharist is. It is the Body and Blood of Christ, that looks like a host or bread and cup of wine, but in fact is the real Jesus. It was a success, to a point. Many Catholics today believe in the "whatness" of the Eucharist. Trouble is this intellectual assent of faith does not move many people to want to go to church to receive the Eucharist.
There is an earlier way of talking about the Eucharist. It is called Consubstantiation. It means that the Eucharist is the way that God is revealed through Christ to us. Or more importantly, it is the way that God especially comes to us. I think that this is a much more valuable way of looking at Communion. Whatness is intellectual. It does not change us much. It only changes the bread and wine. But if you experienced God coming to you in the mass and communion, I think you might want very much to go and receive. Consubstantiation does not quibble about what something is or when it becomes what it is. Consubstantiation is about the dynamic of relationship. You may not know exactly what someone is in any objective fashion. Someone you love may always be a mystery, but if you experience their love for you when you are with them, then you hunger for the time to be with them. God is your spouse. God is Love. Let the mystery be a mystery. The Reformation is over.