Fourth Dimension and Sight

First off- Sorry this is short, extremely tired.

Billy, is an optometrist. The job of an optometrist is to make people see better. In this story, many lessons are taught in a fourth dimension setting, something we humans can't see. One major example is the metaphor the tralfalmadorian guide told the audience to imagine:

"The guide invited the crowd to imagine that they were looking across a desert at a mountain range on a day that was twinkling bright and clear. They could look at a peak or a bird or a cloud, at a stone right in front of them, or even down into a canyon behind them. But among them was this poor Earthling, and his head was encased in a steel sphere which he could never take off. There was only one eyehole through which he could look, and welded to that eyehole were six feet of pipe. 

This was only the beginning of Billy's miseries in the metaphor. He was also strapped to a steel lattice which was bolted to a flatcar on rails, and there was no way he could turn his head or touch the pipe. The far end of the pipe rested on a bi-pod which was also bolted to the flatcar. All Billy could could see was the little dot at the end of the pipe. He didn't know he was on a flatcar, didn't even know there was anything peculiar about his situation" (115).

To me, this quote is simply incredible. It is also evidence of how sight plays a role in this novel. This quote is very accurate in saying that those who can't see the fourth dimension are stuck viewing life as it goes; unable to move, unable to change it, unable to do anything. In other words, according to this fourth dimensional mindset, we Earthlings can't see what's going to happen, change what is going to happen, or ever escape the third dimension. Vonnegut, through Billy, time travel, and the Tralfalmadorians is communicating just how severe our tunnel-vision world is to us, and the fact that no one tends to think of this as a 'peculiar' situation. This truly is something interesting to have in the book, but it is true that humans have tunnel vision when thinking about a fourth dimension, and that is impossible to change; therefor I wonder why Vonnegut put so much emphasis on this.