Money is the only kind of power the white people in this play understand.

Money drives us crazy. That is the message of Two Trains Running, the seventh play in August Wilson's series The Pittsburgh Cycle. The characters can't stop thinking about it.

The main character, Memphis, the owner of the restaurant in which the play is set, is very clear about how much he paid for the building he owns and what, according to the market, he should get if he sold the property. The young ex-con who shows up at the restaurant in the first act, Sterling, is looking everywhere for a job because he desperately needs money. (He also went to prison for robbing a bank.) The guy who runs the numbers racket for black folks, Wolf, has sacrificed erotic pleasure for money. And West, the man who owns the neighborhood's funeral home, the richest person in the play, who, since being widowed, has substituted the stuff that makes the world go round for marital happiness.

All of the onstage characters in Two Trains Running, which opens at Seattle Rep on January 12 and runs through February 11, have some sense of money's illusoriness and the fact that death is the final truth, but they can't stop pursuing or thinking about it. Aunt Ester, the 349-year-old oracle of the neighborhood, has only one message to everyone who visits her: Throw that damn money away. And though her wisdom is understood, it's hard to put into practice.

Two Trains Running is a pessimistic play with a happy ending. I haven't seen the Rep's production yet, but I regard the text as a work of literature.

The French economist Thomas Piketty made a bold assertion about money in literature in his 2013 best seller Capital in the Twenty-First Century. He claimed that the difference between 18th- and 19th-century literature and the literature of today is that the former had a sense of what things cost and the latter does not. What this means is, you could read a novel by, say, Jane Austen and get a pretty good idea of how much money you would need to make life comfortable in her world. But if you read a novel after World War I, money as an exact measure of social position and opportunities disappeared. What does $2.35 mean to a character in Jonathan Franzen's novels? It's hard to tell. Your guess is as good as mine.

There is no such mystery in Two Trains Running. Wilson lets us know on the first page exactly what you can purchase with $2.35. If you pay that amount of money in Memphis's restaurant, you will be given a serving of meatloaf with two sides. And it's not just the menu that has exact prices. Memphis also knows his building is worth no less than $25,000. Obviously, Piketty has never read Wilson, because he would have had to make Two Trains Running the exception to his otherwise excellent hypothesis.

Every dollar in this play is evaluated. When you lose one or two or three bucks, you know exactly what you are losing in terms of purchasing power. And purchasing power is social power. And social power is the only power that the white people in the play understand. It is this understanding that makes Memphis rich and provides Two Trains Running with the saddest happy ending in all of black American literature.