But Why Sandman?

I agree with Stephanie's understanding of the Sandman, however I think that Coppelius is meant to symbolize something else. It is strange that he reappears in the story as a barometer salesman. Overall, I am just very confused as to he wrote this allegory, and most of all, why he called it the Sandman.

I suppose Sandman could be a reference to the way that scientists can throw sands in your eyes and confuse or blind you as Nathaniel was blinded.