Humans cannot imagine higher dimensions. Our sences, and minds are bound with 4D space. We can't even imagine 2 and 1D. What we think 2D is, like this what You see on Your computer, is really 4D too. Why? couse Your looking on it from a distance, which is one more dimention. 2D can't be imagined as a thin line, couse it has no thickness. If sb. try to imagine line with no thickness, he'll see nothing. So, we can only see how does the 4D looks like, and nothing more. Sad isn't it?