As for his suspicions, once on terra firma, once that he had seen the indifferent, if not friendly, appearance of his hosts, his anxiety had quite disappeared, or rather, at sight of the goat, had turned to appetite.
Believe me, and take comfort, this is better for me than tons of gold and cases of diamonds, even were they not as problematical as the clouds we see in the morning floating over the sea, which we take for terra firma, and which evaporate and vanish as we draw near to them.
Four shallops came off with very little noise alongside the lugger, which, no doubt, in acknowledgement of the compliment, lowered her own shallop into the sea, and the five boats worked so well that by two o’clock in the morning all the cargo was out of The Young Amelia and on terra firma.
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.