Salespeople have a language and a culture all their own, and their poet laureate is David Mamet. His classic 1984 Pulitzer Prize-winning play Glengarry Glen Ross has inspired a generation of deal-closers. This month, it will receive its first major Broadway revival, starring Liev Schreiber as Richard Roma and Alan Alda as Shelly Levene (the characters played in the movie version by Al Pacino and Jack Lemmon, respectively).

For salespeople, Glengarry's appeal comes from some combination of its familiarity, humor, exaggeration, and foul-mouthed language. "It's a favorite among everyone I know in sales," says Jennifer Moran, the southern New Jersey territory manager for Office Business Systems in Pine Brook, N.J., who drives her team to drum up "Glengarry leads" whenever anyone in the office hits a slump.

Yet some gifted salespeople think many of their peers take the wrong lesson from the play -- namely, be ruthless. "'Always be closing' is used all the time because it sounds good," says Haim Chasman, CEO of New York City-based Mall Marketing Systems, referring to Mamet's iconic mantra. "But none of the guys in Glengarry believe in the product, and that's essential to really be successful."

Glengarry has become a cultural touchstone because it depicts capitalism in its rawest dog-eat-dog form, while acknowledging that success in sales is often the key to securing a piece of the American dream. "I go over the play every day and there is no bottom to it," says Alda. "Twenty years later, it's more to the point than ever." Schreiber, who is writing a script about How to Win Friends & Influence People author Dale Carnegie, says that Glengarry (and Death of a Salesman) has enduring appeal because "salespeople are an ideogram for social interaction -- even if we don't want to admit that we are always pitching ourselves to the world."

Click here to read interviews with Glengarry stars Alan Alda, Liev Schreiber, and other cast members.