Eucharist - a Mystery

Talk about sharing what your faith means to you! I can grasp why we never talked about religion when I was growing up in Ireland.  Mainly because we couldn't (or at least I couldn't) share our most intimate feelings with someone who might not grasp them. I lived in a parish where our pastor believed that children should receive the sacraments when they could express an understanding of them, not when they arrived at an age established by rules. Consequently, several of my classmates and I received the sacraments of Penance, Eucharist and Confirmation at the age of seven.

While I agree with his approach in theory, I cannot guarantee that I understood what the words really expressed. How many of us really can say that we understand the mystery of the Eucharist today?  Who can explain the mystery of transubstantiation? Can I explain my belief in the Real Presence of Christ in the bread and wine after the words pronounced over them by the celebrant at Mass?