The things come from another planet, being able to live in interstellar space and fly through it on clumsy, powerful wings which have a way of resisting the aether but which are too poor at steering to be of much use in helping them about on earth. I will tell you about this later if you do not dismiss me at once as a madman. They come here to get metals from mines that go deep under the hills, and I think I know where they come from. They will not hurt us if we let them alone, but no one can say what will happen if we get too curious about them. Of course a good army of men could wipe out their mining colony. That is what they are afraid of. But if that happened, more would come from outside—any number of them. They could easily conquer the earth, but have not tried so far because they have not needed to. They would rather leave things as they are to save bother.