In the "Preface to Second Edition," de Lubac puts into words the project of "return to the sources" (pp. 9-10) that describes well his overall project. He speaks as a historian, but also as a theologian, even more basic as a Christian. I found resonance in his words:

Historians must first of all make contrasts stand out, if they are not only to trade in banalities. But they should not close their eyes to more fundamental continuities! As for me, my gaze will always end up fixed on the history of human thinking itself, and even more on that of Christian theology. I will always find peace and joy in contemplating them. Amid so many varied riches that claim my attention, I will always seek to act like a child of Plato, that is to say, every time that there is at least the possibility of so acting, I will not make a choice. A unity that is too quickly affirmed has no power to inspire, while eclectism has no impact. But the methodical welcoming of contrasts, once understood, can be fruitful: not only does it guard against over-eager partiality; not only does it open up to our understanding a deep underlying unity: it is also one of the preconditions that prepares us for new departures.

Here is a concept of tradition that does not close back in upon itself, but that provides the conditions to save the repetition of the past from a nostalgia that empties those who proceeded us of their power in the name of sustaining their form. It has the typical de Lubac paradox: by seeing contrasts theologically, one can grasp a deep underlying unity. This unity often surprises us, and God gives us memories of the past, both our own personal histories and the larger histories of which we are part as Christians, as the precondition that allows us to faithfully meet challenges that come after.