How does the Time Traveler explain that time travel is possible to his guests?

       The time traveler is hosting a dinner at his home, yet he brings the other men there for another reason. After dinner he begins discussing time travel. He starts by saying that a cube takes space, like on a graph. It can go left and right on the graph (1st dimension). It can go up and down. (2nd Dimension). It can go a distance, or the y axis (3rd dimension). He goes further to say that time is designated as the 4th dimension. His reasoning is that if you can move in the first three dimensions why not the 4th? His colleagues argue that "...if time really is the fourth dimension, why is it, and why has it always been regarded as something different?"(9) The time traveler finishes by saying that each dimension has its own difficulty to maneuver.