But it also contains all possible contradictions and negations of all possible secrets - so, you don't know which is the "true" secret.

I love this response. Deflates the enchantment right out of Borges' library (and Nietzsche's eternal return, and fantasies about mystical significance of pi), which always bothered me somehow anyway.

This is directly mentioned in Borges' story

No doubt it's directly mentioned in that blasted library too, along with any number of perfect refutations.

Or the typewriter’s monkey