Now there's a problem...No one witnesses it...
Let's try something...Here it goes...I'll pretend my old truck will turn into a Cadillac Escalade...
There, it's done...Do you see it??? Ain't it pretty...It's fast too...Want a ride???
There's your transubstantiation...
If your old truck was transubstantiated into a Cadillac Escalade it would continue to perform like an old truck though. In a very loose sense it’s like being born again, there’s no physical change in the person but there is a very real change. I repeat, in a VERY loose sense.