“It’s cooler. And our voices are so much louder. That faded quality⁠—it has altogether gone. And the feeling in one’s ears and throat.”

I had not noted that, but I did now.

“The air is denser. We must be some depth⁠—a mile even, we may be⁠—inside the moon.”

“We never thought of a world inside the moon.”

“No.”

“How could we?”

“We might have done. Only⁠—One gets into habits of mind.”

He thought for a time.

“ Now ,” he said, “it seems such an obvious thing.