"Well, I guess if you want to put it into mathematical terms you'd square the square. But you can't take a pencil and draw it the way you can the first three. I know it's got something to do with Einstein and time. I guess maybe you can call the fourth dimension Time."
That great whooshing sound you hear is the noise of 10 million readers deciding to just go ahead and be English majors.
http://jezebel.com/5013495/a-wrinkle-in-time-quit-tesseracting-up