When I was about 8 or 9 years old I read "The Boys Book of Space" and was really inspired by it. One of the articles was about astro-navigation, dealing with the principle of thinking in 4 dimensions.
4-dimensional thought means aiming at where the target is GOING to be when the projectile gets there, not where the target is now. There's no point in going to where Mars is now because Mars won't be there by the time you arrive.
As a kid I got so much into this idea that walked across roads knowing that I could get to the other side without being run over as long as all the cars kept moving at the same speed, there would be a clear path in 4D. However, the car drivers were thinking in 3 dimensions and so skidded to a screeching halt even though they were in absolutely no danger of hitting me. I felt very frustrated by everybody else's inability to "see" 4D in their mind's eye.
Another 4D picture I could see in mind was how a tetrahedron might look if rotating in the time continuum. I realised that a tetrahedron rotating would look like a pentagram. No-one else knew what I was talking about.
These days, thanks to Google Sketchup it's possible to sketch my ideas in a moving video form, so here it is.