A note on page 8 of the Cambridge edition of The Gay Science:

Plutarch reports that in a temple in the Egyptian city of Sais, there was a veiled statue of the goddess Isis with the inscription: "I am everything that is, that was, and that will be, and no mortal has ever rasied my veil." In his Critique of Judgement Kant says that this inscription is the "perhaps most sublime thing ever said."

To say the sublime is to attempt to say the unsayable, or, more properly perhaps, to indicate that the unsayable is unsayable. Wittgenstein:

What we cannot speak about we must pass over in silence.