Horace, you know if you could see the fourth dimension, would you know what the hell you were looking at? NO! When an ant looks at you, does it distinquish your arm from your head, or your foot from your arm. The reality is no, cause its unable to comprehend higher dimensions that the one it is in already. Similarly, we humans cannot either, hence we develop thought experiements, and some other methods to understand the reality behind the 4th dimension. Why stop there, string theory agrees upon 6 dimensions.