I've been thinking about this for a while...a 2 Dimensional being should have no ability to comprehend the concept of a Z Axis. A square shouldn't know what the hell "up" is, as it can't perceive up or down. We have always though we lived in third dimension, where we can understand 3 axes, but the fourth dimension, Time, is understandable to us. We can see it, observe it, and even measure it, yet we can't manipulate it. But why? If we can walk side to side, forward and back, and up and down, whats stopping us moving through time, or at least observing different places in time? According to the theory of relativity, time and space are one. So since we can observe two places at the same time, why can't we observe two times at the same place? Time manipulation has even observed, and breaking the speed of light should theoretically cause time to move backwards relative to the observer (That also explains the infamous "flying around the world to reverse time" in Superman, he didn't reverse the Earth's rotation to change time, he was just flying faster than light, making it looklike the Earth was spinning backwards. fun fact!).