What is the specific significance of the final sentence of the story "Paul's Case"?

"Then, because the picture making mechanism was crushed, and disturbing visions flashed into black, Paul dropped back into the immense design of things."

I think the disturbing visions were the scenes of the Adriatic water and the yellow of the Algerian sands, both the images he realizes he will never see now that he has jumped in front of the train. These images are disturbing because they will haunt him even in death because he will never see them.

When the disturbing visions flash to black, this is a reference to his life on Cordelia street, where there are no cut flowers and no colour. Now, he is dropped back into the colourless and immense design of things which he had tried to escape by killing himself.

Or, : ) he could be dropped back into the immense design of things by realizing he will never get to see the Adriatic water or the Algerian sands and therefor he is exactly like the people who he despises. He sees his peers, teachers and father as people who just live life by doing what they are supposed to and now he has ended his life before doing anything of significance and is just the same as the others.