Science is the midwife of metaphysics. However much it might protest that it confines itself to physical realities only, science cannot help but provoke metaphysical questions in the human mind. To be sure, when it confines itself to its own specialized sphere, each science is strictly physical, physical both in the scope of its investigation and in the results and data those investigations produce. But science's ultimate import is always metaphysical.

At least among professional theologians, Hans Urs von Balthasar tends to perplex more than he manages to inspire. To be sure, he can inspire. For example, the journal he founded, Communio, now appears in twelve languages (including Arabic). But subscribers never exceed the number - itself already quite small - usual for most other professional theological journals. More to the point, few Catholic departments of theology in Europe or North America consider it essential to have a Balthasarian expert on their respective faculties (a similar attitude towards liberation theology, transcendental Thomism, or feminist theology, by comparison, would seem vaguely revanchist).

To some extent, however, this situation has begun to change. In fact, this volume in the Cambridge Companion series testifies to what seems to be an incipient sea change in attitudes towards this unusually productive, subtle, and complex theologian. For that reason, the editors wish to stress that this collection of essays by a wide array of scholars wishes not so much to inspire as to address the perplexity that seems to be an inherent part of everyone’s reaction to Balthasar’s thought. We make no claim to have resolved the perplexity that so many readers feel upon encountering his theology for the first (or even umpteenth) time.

Readers who have read all, or even most, of the chapters of this volume will already have come to the conclusion of this chapter: Hans Urs von Balthasar has bequeathed to the world a theology that is extremely hard to assess. Subtle and vast, his theology is also composed of parts so densely and tightly interwoven that no component can be jettisoned, or even much altered, without affecting the whole. For that reason (among others), judging the future influence of his theology is even more difficult. Take, for example, this programmatic manifesto, tucked away in one of his more obscure writings, where he is speaking of the effort it cost him to revise his one-volume dissertation, Prometheus, into the large, three-volume work, Apocalypse of the German Soul, a labour he undertook, he says, because he was resolved to 'rebuild the world from its foundations'.

But how does an outsider to his project even begin to assess such a programme? At least for Balthasar himself, it would seem that the only way of guessing what the future might hold for his theology is to see if he will finally succeed in ‘rebuilding the world from its foundations’. Ambitious Balthasar certainly was, but will he prove successful in his ambitions? Very few readers, and among them only the captious ones, will deny that Balthasar was a great theologian; but will he prove an influential one in the long run?