He said: This is my Body; therefore the Eucharist is not the figure of his Body and Blood, as some have said, talking nonsense in their stupid minds, but it is in very truth the Blood and Body of Christ.’
St. Macarius the Great (4th Century)
Ouch! Maybe a little harsh, but clearly nobody can say that Aquinas made transubstantiation up, or even sillier, that the doctrine was invented at Trent. The reality is that the Church explicitly believed in the literal and physical presence of the very Body and Blood of Our Blessed Lord in the elements of the Eucharist from a very young age.