non-Catholics and communion on the Camino

[Rosina Lila]

Although I have been a Catholic all my life, and a sincerely devout one, and
have met the Pope, for whom I have the deepest affection and reverence, at
least three times,  I do not know what "transubstatiation" is, nor do I
believe that anyone in my circle of friends would know or has ever spoken
about it.  I asked some of my relatives, all devout Catholics and highly
educated, and they were just as befuddled as I.
 -I would ask my parish priest about it ,  but we always have so many other
practical needs and things to talk about it that I am sure I'll not have an
opportunity to do so.-  Is this  in the Gospel or is it a man-made concept?

A simple definition/description would be appreciated.
Thanks!

Rosina