What is the most important line in Dubliers?

As one of the most famous short story collections ever written, The Dubliners by James Joyce is full of important lines and quotes, but arguably the most important is from the last paragraph of the last story "The Dead. " It describes the snow falling not just outside of the main character, Gabriel's window, but all across Ireland. Even on the grave of the man he has just found out his wife was always in love with.

Yes, the newspapers were right: snow was general all over Ireland. It was falling on every part of the dark central plain, on the treeless hills, falling softly upon the Bog of Allen and, farther westward, softly falling into the dark mutinous Shannon waves. It was falling, too, upon every part of the lonely churchyard on the hill where Michael Furey lay buried.

It is followed by the line.

His soul swooned slowly as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead.

In the context of the story, this blanket of snow is a metaphor for how numb Gabriel feels after finding out he has never experienced the true love of his wife. In fact, it must seem to him that not only is his life falling apart, but that he can't do anything about it. The man responsible for his misery is buried deep under the ground.
On a wider context it tempers the nostalgic lens through which James Joyce, who hadn't lived in Dublin for a number of years, writes about his home city. Yes, he can recall wonderful images and wonderful times, but he needs to remind himself that they are all just part of his memory and not necessarily his reality.