There is something I ‘know,’ which is that spatial dimensions beyond the Big 3 exist. I can even construct a tesseract or hypercube out of cardboard. A weird sort of cube-within-a-cube, a tesseract is a 3D projection of a 4D object in the same way that 
is a 2D projection of a 3D object. The trick is imagining the tesseract’s relevant lines and planes at 90 degrees to each other (it’s the same with and a real cube) because the 4th spatial dimension is one that somehow exists at perfect right angle to the length, width, and depth of our regular visual field. I ‘know’ all this just as you probably do…but now try to really picture it. Concretely. You can feel, almost immediately, a strain at the very root of yourself, the first popped threads of a mind starting to give at the seams.”
— David Foster Wallace, Everything and More
Lisa Marie Blair 