She thought a moment, and shook her head.
"What a story," she murmured, "what an incredible, horribly fascinating story that would make, if it could ever be known, or written! Think of the ebb-tide of everything! Railroads abandoned and falling to pieces, cities crumbling, ships no longer sailing, language and arts and letters forgotten, agriculture shrinking back to a few patches of corn and potatoes, and then to nothing at all, everything changing, dying, stopping--and the ever-increasing yet degenerating people leaving the city ruins, which they could not rebuild--taking to the fields, the forests, the mountains--going down, down, back toward the primeval state, down through barbarism, through savagery, to--what?"
"To what we see!" answered the engineer, bitterly. "To animals, retaining by ghastly mockery some use of fire and of tools. All this, according to one theory."
"Is there another?" she asked eagerly.
"Yes, and I wish we had the shade of Darwin, of Haeckel or of Clodd here with us to help us work it out!"
"How do you imagine it?"
"Why, like this. Maybe, after all, even the entire black race was swept out along with the others, too. Perhaps you and I were really the only two human beings left alive in the world."
"Yes, but in that case, how--?"
"How came they here? Listen! May they not be the product of some entirely different process of development? May not some animal stock, under changed environment, have easily evolved them? May not some other semi-human or near-human race be now in process of arising, here on earth, eventually to conquer and subdue it all again?"
For a moment she made no answer. Her breath came a little quickly as she tried to grasp the full significance of this tremendous concept.
"In a million years, or so," the engineer continued, "may not the descendants of these things once more be men, or something very like them? In other words, aren't we possibly witnessing the recreation of the human type? Aren't these the real pithecanthropi erecti, rather than the brown-skinned, reddish-haired creatures of the biological text-books? There's our problem!"
She made no answer, but a sudden overmastering curiosity leaped into her eyes.
"Let me see them for myself! I must! I will!"
And before he could detain her, the girl had started back into the room whence they had come.
"No, no! No, Beatrice!" he whispered, but she paid no heed to him. Across the littered floor she made her way. And by the time Stern could reach her side, she had set her face to the long, crumbling crack in the wall and with a burning eagerness was peering out into the forest.