There are things we are not meant to understand. God's universe will always be beyond our comprehension. For example, why is the sky blue? There is a scientific answer to that question, something about the way light refracts through water molecules in the atmosphere. Google it if you really want to know.
But after you find the answer, you still won't know why. You'll know how. But why? Why isn't the sky green after the sunlight moves through the molecules? What is blue? Another example. We know how planes fly, lift and drag and all of that. But we really don't know why. Or maybe we know why, lift and drag and all of that, but we don't know how that would hold up all that giant tonnage, and by tonnage, I am referring to the people who can't even fit into an airplane seat and all the luggage everyone tries to get away with bringing on board. People would still carry an upside down chicken on board if they could and a goat on a string.
So, I have often talked about the Catholic use of the term "Sacred Mystery", which means, in Catholic, that which you will never truly understand as a human being and can only guess at the reasons edges so you may as well just let it go.
Or keep trying. I suppose you could end up being a Doctor of the Church like St. Thomas Aquinas. Meanwhile, all the best with the Sacred Mysteries.
I understand what you say by Sacred Mystery, my problem has always just been actually believing and feeling that the bread and wine have become Christ. I want to, I always have, but it's never clicked. (I'm a lapsed cradle Catholic with 12 years of Catholic school.) Any suggestions on how to get my brain/soul/heart/whatever make the leap?
This is a huge problem. It's really the very core of the faith, so you're going to have to get on board and jump on the Sacred Mystery (just let it go and believe it) bandwagon.
The good news is that you are very much not alone in your difficulty. First of all, the whole Protestant Church and all its denominations don't believe in transubstantiation (the $10 word for the miracle that occurs during each Mass). They believe it's all just symbolic.
They are correct in believing that within the walls of their own church. Only a priest can perform the miracle, so there is no transubstantiation taking place over at the Lutheran church.
But then, you're not a Protestant. You can't get away with going the symbolic route.
Still, you're not alone. You may be surprised to find that, now and again, a priest in the process of performing the miracle is having severe doubts.
And every now and again, his doubts will be totally alleviated by what is commonly known as a "Eucharistic Miracle". I say "commonly" know, because it has happened enough times to have the name "Eucharistic Miracle".
The very first one, as far as I can remember, happened in 700 AD to a doubting monk saying Mass. If I remember correctly, the Host turned into actual flesh and began to bleed. Finally, sometime in the middle of the 16th century someone thought to test it. Yes, it was still around! Details are coming back to me....the blood was in five big sort of drops and, of course, everyone put that together with the Five Wounds of Christ.
Since that time, it has been tested several times, as late as the 1970's and maybe even again in the 90's. The results have never varied. The flesh is human heart tissue and the blood is type AB.
So now we know Jesus' blood type.
It's happened quite a number of other times, almost always, if I'm not mistaken, to a priest struggling with the same doubts you are having. And now, we have it on film!
In this instant, the Host changed to flesh and bled, but after they put it in a Monstrance for the faithful, it also began to glow and pulsate like a beating heart. And here it is:
I hope this helps.
I do understand your difficulty. I've always felt a little sorry for St. Thomas the Apostle who is forever known as "Doubting Thomas" because he was understandably dubious about anyone returning in tact from a crucifixion. I like to give Doubting Thomas the benefit of the doubt. He wanted some flesh and blood proof and Jesus was happy to oblige. Then and now.