THE QUESTION to which this paper is devoted, namely, the possibility of a natural knowledge of God apart from faith, is one that might be thought to be closed for Catholic theologians. dogma of Vatican I does not appear to allow of any compromise: The same holy mother Church holds and teaches that God, principle and end of all things, can be known for certain by the natural light of human reason from created things; 'for His invisible qualities, since the creation of the world, have been seen as discerned through the things that have been made' (Rom 1:20) (DS 3004). Nor does a quick reference to the first chapter of the Epistle to the Romans give any encouragement to a reopening of the question. Moreover, Catholic exegetical tradition seems to be quite firmly against it. Vatican I, a little later in the dogmatic constitution quoted above, interprets Rom 1:20 as speaking of a purely natural knowledge of God, thus reflecting the common exegesis of its time. Nor does the position seem to have changed. most recent Catholic commentary in English has this to say: There is no question here either of knowledge through a positive revelation or knowledge by faith. Yet in real life it is only those who already believe in God by faith who claim that He can be known by reason. aim of this paper is. to re-examine Rom 1 and thus attempt a reformulation of the relation of faith and reason in regard to the existence and nature of God. It is hoped that this reformulation will be seen as a valid development of the doctrine of Vatican I. At the outset it must be remembered that in Rom 2:13-15 Paul says that some of the Gentiles obey the law that is written on their hearts. Natural knowledge of God, then, will come from two directions: from without, i.e., from the contemplation of the universe, and from within, i.e., as a moral imperative. one demands the other. Although this paper is concerned mainly with the knowability of God from the contemplation of the universe, due account will be taken of the role of conscience and moral decision. 1 relevant passage, from DS 3015, is: Quocirca Apostolus, qui a gentibus Deum 'per ea, quae facta sunt' [Rom 1, 20], cognitum esse testatur, disserens tarnen de gratia et ventate, quae 'per Jesum Christum facta est' [cf. Io 1, 17], pronuntiat: 'Loquimur Dei sapientiam in mysterio ' 2 J. A. Fitzmyer, in the commentary on Romans, Jerome Biblical Commentary (Englewood Cliffs, N.J., 1969) 2, 296.