It's a common misconception, often attributed to the book or its characters due to its romantic and poetic sentiment.
The quote is a variation of a passage from the book "Villette" by Charlotte Brontë, where the character Lucy Snowe reflects on her own heart:
> *"And how much, how much there was in that heart, locked away as in secret chambers, hidden as in the recesses of a tomb! How much in it, too, that could never be revealed, that could never die, that could never be forgotten!"*
This passage captures a similar sentiment to the quote you mentioned, but the exact wording is different. The quote itself does not appear in either "Jane Eyre" or "Villette."