On this day, the 31st of October, All Hallows' Eve, many of our Protestant brothers and sisters celebrate Reformation Day - the momentous day in 1517 when the Augustinian friar Martin Luther nailed his famous 95 Theses to the door of the Castle Church in Wittenberg, Germany.

The date always brings to mind my return to the Catholic Church some thirty years ago. Major factors in that homecoming were nagging questions about the proper relationship between Sacred Tradition and Sacred Scripture. (Another was a growing hunger for the Eucharist, which was less a matter of the head than of the heart; as Pascal said, the heart has its reasons, of which reason knows nothing.)

I'll always be grateful for those evangelical Protestant churches that nurtured me in the faith for so many years, including instilling the sound practice of daily Bible reading. In the mid-1990s, however, after having gravitated to the Reformed/Presbyterian wing of evangelicalism, I began a quest that eventually would lead me to take my place among the ranks of "reverts" to Catholicism.

Prior to that return, I was becoming increasingly concerned that the decades-long crisis of authority within Mainline Protestantism was also beginning to manifest itself in Evangelical churches. Most disconcerting to me was the dawning realization that Protestantism, in whatever form, simply lacked the wherewithal to confront this predicament.

For it was increasingly evident that appeals to the Bible alone, however heartfelt, were proving less and less effective against the corroding acids of modernity.

The question of interpretive authority was the nut the Protestant Reformers couldn't crack, which is why there was no Protestant Reformation (singular), but various Protestant Reformations (plural). The common cry of sola scriptura couldn't provide a way for the various Protestant camps to settle their differences - and not just over nonessentials, but over such central doctrines as Baptism and the Eucharist.

No way, that is, except by recourse to the sword (the literal one, not the sword of the Spirit), a bloody affair in which Catholics lamentably also played a major role.

It was through a reading of the new Catechism of the Catholic Church - a great symphony in four movements, as John Paul II described it - that I took my first tentative steps into the Great Tradition. There, I discovered what Jaroslav Pelikan meant when he referred to Tradition as the living faith of the dead (in contrast to traditionalism, which he defined as the dead faith of the living).

In the Catechism, the beauty of the Great Tradition seemed to shine forth from every page, confirming the truth of the Austrian composer Gustav Mahler's observation that tradition is not the worship of ashes, but the preservation of fire. (Mahler was Jewish, so knew a thing or two about the importance of tradition.) I concluded that this is what Jesus must have been referring to when he promised his disciples that when the Spirit of truth came, he would guide them into all the truth.

(John 16:13)

But something else was beginning to gnaw at me, which, if you think about it, is the most obvious question you can ask about the Bible: Where did it come from? We, of course, share with our orthodox Protestant brothers and sisters the strong belief that the Holy Spirit is the ultimate author of Sacred Scripture, that it is divinely inspired.

But how did the Church come to recognize and authenticate the twenty-seven books that comprise what we know today as the New Testament? After all, the Bible did not come with an inspired table of contents.

Moreover, there doesn't seem to be a sure-proof, objective standard by which to establish the Biblical "canon." Witness Luther's own struggles with whether that "right strawy epistle" of James (and not just that epistle) should be included in the Bible.

So, when the Protestant reformers appealed to sola scriptura, they seemed to be taking an awful lot for granted. For implicit in their accep...