The theorem of the supernatural

One of the things I need to get clear about in Lonergan is what he calls the theorem of the supernatural. The other day, during Nelson's homily, I thought I got a little window onto this theorem. Nelson was quoting St Paul: "What is it that we have not received?" It reminded me of Lonergan speaking about the problem faced by early Christian reflection on grace: how to distinguish grace from the fact that everything is received, everything is gift? The answer is probably a difference in proportion: nature and supernature, what is proportionate to human nature and what is not proportionate to it, what is simply beyond it. A distinction, therefore, between two orders. Not that there is or was a state of pure nature; but that we need this kind of distinction if we are to handle reflection on the Christian revelation.