Article 4, Q 74, Tertia ParsThe question is whether it is mo' better to use leavened or unleavened bread. Much to everyone's surprise He comes down on the side of unleavened bread, but in the course of his discussion he says it would be a sin for Greek Priests to use unleavened because she should play by the rules of their team. (Dawg paraphrase)
I always understood this to mean that he thought there really were Greek Priests.
To tell the truth, all I remembered was the question was in the 70's, AND the opinion about playing team ball.
"I always understood this to mean that he thought there really were Greek Priests."
I think its very likely he did. In his days, the schism wasn't as absolute as we might often believe. Indeed, into the late 1600s there were ties of communion between various Orthodox bishops and Latin Rite bishops, even in the Aegean. In fact, as recently as within the past 200 years there were joint celebrations of feastdays on various of the Aegean Islands. But I do think you'll find that from about 1100 on, Rome itself felt that the Orthodox were outside The Church, even if on a local basis that wasn't so true.
Take a read of the writings of Pius IX and Leo XIII. I think they are pretty clear that they believe the Orthodox are damned.