"There is a tendency among some historians to make the identification, to say that the Catholic Church taught this or did that, when all that one can be certain of is that particular men, baptized Christians, occupying a particular role in the ecclesiastical system, did this or taught that. The Church, of course, to teach at all, must teach not only by the extraordinary pronouncements of ecumenical councils or Popes but also by its ordinary organs, the bishops, who will rely on the common opinions of the theologians. Yet no great original theologian, not even an Augustine or a Thomas, has been able to write extensively on theology without writing what later has been determined to be heresy. Only the Church is free from error. What is the teaching of the Church becomes itself a theological question."