But an objection will undoubtedly be raised here: Is it possible to go beyond nature? We do not hesitate to answer plainly: Not only is it possible, but it is a fact. Again it might be said, is this not merely an assertion; what proofs thereof can be adduced? It is truly strange that proof is demanded concerning the possibility of a kind of knowledge instead of searching for it and verifying it for one’s self by undertaking the work necessary for its acquisition. For those who possess this knowledge, what interest can there be in all this discussion? Substituting a “theory of knowledge” for knowledge itself is perhaps the greatest admission of impotence in modern philosophy.
Moreover, all certitude contains something incommunicable. Nobody can truly attain to any knowledge other than by a strictly personal effort; all that one can do for another is to offer him the opportunity and indicate the means by which to attain the same knowledge. That is why it would be vain to attempt to impose any belief in the purely intellectual realm; the best argument in the world could not in this respect replace direct and effective knowledge.
Now, is it possible to define metaphysics as we understand it? No, for to define is always to limit, and that with which we are concerned is, in itself, truly and absolutely unlimited and cannot be confined to any formula or any system.