.. I'm about at the halfway point in understanding this concept, as I no doubt will continue to be, 10 years from now! {a 30-35 'sec' download}.
http://www.sciencenews.org/view/generic/id/35740/title/Seeing_in_four_dimensions

Thanks. I'll read this this weekend. My first thought was to move through computer generated 3-D slices, maybe taking different paths to get an idea of the local 4D, then i seen that caption 'not so easy' and laughed. that's true...
 
i don't try to visualize and just take the algebra as it comes after three dimensions, ala Riemann, but looks like a good article.