For not only do fabulous rumors naturally grow out of the very body of all surprising terrible events,—as the smitten tree gives birth to its fungi; but, in maritime life, far more than in that of terra firma, wild rumors abound, wherever there is any adequate reality for them to cling to.
There are no more uses of "terra firma" in the book.
Show samples from other sources
When the elevator thumped to a stop, Langdon was relieved to feel terra firma beneath his feet.
Dan Brown -- Angels & Demons
God Almighty, I’m glad I’m right here on old terra firma.