Zacharias Ursinus (1534-1583), the author of the Heidelberg Catechism (1563), wrote a lengthy commentary on this catechism. In the discussion of the Lord's Supper, he provides the following reason why Transubstantiaion could not have taken place at the Last Supper (and, as a result, the supper itself could not have been a propitiatory sacrifice):
If the bread is properly the body,
and the cup the blood of Christ, it must follow, that in the first supper the
blood was separated from the body of Christ, and then they are both exhibited
to us separately, as they are separate signs. But neither was the blood in the
first supper without the body, nor is the body of Christ now given to us
without the blood; for then at the first supper Christ was not yet dead, or
does he now die any more. The bread is, therefore, the body, and the cup the
blood of Christ, not properly, but sacramentally. (The Commentary of
Zacharias Ursinus: On the Heidelberg Catechism—The Protestant Christian
Doctrines, Dating to 1563 [trans. G. W. Williard; Pantianos Classics,
1888], 404)
