Well, let me mention that "transubstantiation" is not capitalized, even among the different capitalizations that Catholicism makes on its own. Transubstantiation is one way of trying to understand the mystery of the Real Presence, but not the only way of understanding. I have no problem with Thomas's writing about transubstantiation, but I understood more by learning about Thomas's experience of the Real Presence and his response that his work was but straw in the presence of the Real Presence.