In April 1615, St. Robert Bellarmine wrote a letter to the author of a book which had defended the Copernican view of the universe, clearly addressing the letter to Galileo as well. St. Robert Bellarmine fulfilled a role in the Church of his time similar to that of Cardinal Ratzinger in our own time. He was a man of great intellect and profound devotion. He was well informed about the state of contemporary scientific endeavour and seems to have had quite cordial communications with Galileo. His letter is strikingly modern, and very concisely presents an answer to the debate as it had come to be presented.
“..It seems to me that your Reverence and Signor Galileo act prudently when you content yourselves with speaking hypothetically and not absolutely, as I have always understood Copernicus spoke..”
This is a reference to the fact that the Copernican view was an interpretation of astronomical observations. At least one other successful interpretation was possible [at that time], and it is in this sense that the Copernican view represented a “hypothetical” rather than an “absolute” claim. To accept it as a “hypothesis” in this sense was quite a different thing than accepting it as being the way things really were. [It did not, either, challenge its scientific status - the sense of the word "hypothesis" might today be communicated better using the term"mathematical model".]
“..If there were a real proof that the Sun is in the centre of the universe ... and that the Sun does not go round the Earth but the Earth round the Sun, then we should have to proceed with great circumspection in explaining the passages of Scripture which appear to teach the contrary, and we should rather have to say that we did not understand them than declare an opinion to be false which is proved to be true..”
This is the critical passage in the letter. Underlying it is the conviction that the results of scientific study and the content of Christian faith are in harmony with each other. When science can offer convincing proof, then it is necessary to look again at the way in which Scripture is understood.
“But I do not think there is any such proof since none has been shown to me..I believe that the first demonstration (i.e. that the Copernican view is a workable hypothesis) may exist, but I have grave doubts about the second (i.e. the existence of proof that the Copernican view is the way things really are); and in the case of doubt one may not abandon the Holy Scriptures as expounded by the holy Fathers..”
This is an important balancing of the previously expressed willingness to look again at the way in which Scripture is understood. In the seventeenth century there really was not any absolute evidence of the earth’s movement through space. In the twentieth century there is, and, if he were alive today, St. Robert Bellarmine would accept that proof and be willing to understand Scripture differently as a consequence.