Paul Vlachos is a New Yorker who understands The West. And he is a New Yorker who understands New York. Wherever Paul goes, he finds signs of life…I do not always have a theme for these columns. It’s often better to let the photos speak for themselves, maybe with the help of a few pithy facts. My theme for this column, though, is “The 20th Century.” I don’t remember how it popped into my head, but pop it did, about a week ago, and I can’t shake the idea.