I don't plan to read Imagining the Tenth Dimension by Rob Bryanton, but the flash animation on his site purports to help you understand it. I always wondered what the hell dimensions five through ten are supposed to be. This definitely helped me understand that five through ten are speculative bullshit, and probably four. But I'm undecided about four (time). How can we tell if it is something objectively existing outside of ourselves or if it's just our fallible perception?

I especially like how they go through these absurd contortions to define dimensions five, six, seven, eight, nine, then everything previous is encompassed in dimension ten, and finally they refuse to imagine anything further because everything possible is encompassed in ten. Bump that. My refusal begins around 3 and a half.