"Not only invisible," snorted the old man, "but non-existent."
A question was on the tip of the newspaperman's tongue, but before it could be asked the old man was speaking again, asking a question:
"Can you imagine a fourth dimension?"
"No, I can't," said Henry.
"Can you imagine a thing of only two dimensions?"
"Vaguely, yes."
The scientist smote his palms together.
"Now we're coming to it!" he exclaimed.
Henry Woods regarded the other narrowly. The old man must be turned. What did fourth and second dimensions have to do with the Horror?
"Do you know anything about evolution?" questioned the old man.