"That is what I have tried to write about. I wanted to make my readers feel and see that thing from another universe, from beyond space. I could easily enough hint at it or suggest it—any fool can do that—but I wanted actually to describe it. To describe a color that is not a color! a form that is formless! A mathematician could perhaps slightly more than suggest it. There would be strange curves and angles that an inspired mathematician in a wild frenzy of calculation might glimpse vaguely. It is absurd to say that mathematicians have not discovered the fourth dimension. They have often glimpsed it, often approached it, often apprehended it, but they are unable to demonstrate it. I know a mathematician who swears that he once saw the sixth dimension in a wild flight into the sublime skies of the differential calculus.