The Mets' improbable weekend sweep of the Nationals and their steamroller victory over the Marlins on Monday night have made them a first-place team in the National League East and prompted their constituency to believe all things are possible. Those with Mets memories that reach back to before last Thursday have a restored sense of: "It can be done if we just believe." Since that dreadful rain-soaked loss against the Padres, believe has become the primary word in the vocabulary of Mets partisans. Indeed, believe has displaced pitch as the operative verb in their thoughts.

And any time belief or faith is spoken in the same sentence as the Mets, a link to the "Ya Gotta Believe" NL champions of 1973 comes out of hiding. Our brains bring forth images of George Theodore, George Stone, George Thomas Seaver, Yogi, the Wall Ball, Tug McGraw and the three-word phrase that fueled the team's borderline preposterous run to the NL championship.

The phrase is thought by many to have originated with McGraw, the late freebird reliever whose behavior and out-pitch could be described by one word -- screwball. McGraw certainly was responsible for the acceptance and popularity of "Ya Gotta Believe." But he wasn't responsible for what became the Mets' battle cry.

Nor was -- and this is a less renowned scenario -- board chairman M. Donald Grant, the stiff and stuffy Wall Streeter, responsible. Tug and M. Donald played parts in what occurred, but serendipity did, as well.

The story of "Ya Gotta Believe" follows. It is required reading now that the Mets are in position to perform the unbelievable, the unfathomable, the unimaginable and, most of all, the difficult.

The story: McGraw met with a friend, Joe Badamo, midday on July 9, 1973. Bandamo was, among other things, a motivational speaker. After McGraw sought Badamo and admitted to him that his confidence had been pierced by too many line drives, Badamo did his motivational best to resurrect his buddy's on-mound self-esteem. According to Tug himself, Badamo said, "You've got to believe," more than once that afternoon. The words immediately became Tug's mantra.

The Mets were to play the Astros at Shea Stadium that night. When McGraw arrived at the clubhouse that afternoon, he began to spread the word to anyone who would listen, and even those who wouldn't. "You've got to believe," he said, repeating himself and increasing the volume. It was Tug being Tug.

Coincidentally, Grant chose that day to address the team. The Mets had played 80 games and were in last place, 12 games from first. The board chairman wanted his players to know they had the support of an ownership that had witnessed the Giants' resurrection from 13 games out 22 years earlier. Mets owner Joan Payson had owned a share of the New York Giants before they skipped town.

Grant told his players they ought to believe in themselves.

He still was speaking when McGraw began to shout, "Believe ... Ya gotta believe!" while prancing around the clubhouse as only Tug would do. Insulted and angered by what he considered ridicule, Grant walked out. McGraw continued his war dance until Ed Kranepool realized that Tug hadn't meant to mock the boss to his face, but that he merely was continuing his spirited afternoon sermon.

Kranepool, one of Grant's favorites, urged McGraw to explain and apologize, not in that order, to Grant. McGraw did, and then resumed his motivational shouting.

A 2-1 victory in 12 innings that night was seen as an endorsement of McGraw's words. Including that game, the Mets won 10 of 17. One of those victories was a game in Atlanta on July 17 in which they scored seven times in the ninth for an 8-7 victory. It was on that night that Berra may have said, "It ain't over till it's over," referring to the game, not the pennant race.

No matter, the Mets remained incoinsistent until their disabled list eventually shrunk. And when improved performance genuinely fortified McGraw's confidence in September, the team's unexpected one-month renaissance began. Tug bellowed "Ya Gotta Believe!" at every opportunity. And like a Sunday morning television evangelist, he converted his colleagues -- from hopefuls to believers.

Tangible evidence developed with the Wall Ball, the rather remarkable play that convinced the Mets that the unseen hand had changed sides and begun working in their favor.

The Mets completed the process of elimination 11 days later, but much of the doubt had been eliminated in the 13th inning on Sept. 20 at Shea Stadium against the first-place Pirates. A fly ball, hit off Ray Sadecki by Pirates outfielder Dave Augustine, headed for the visiting bullpen. It bounced off the top of the wall and back into the glove of left fielder Cleon Jones. A 7-6-2 relay -- Jones to Wayne Garrett to Ron Hodges -- cut down Richie Zisk at the plate and preserved a tie score. Hodges drove in the decisive run in the bottom of the inning for a 4-3 victory.

Had Augustine hit the same pitch with the same swing in June, the ball likely would have carried over the fence. That, or Jones would have misplayed the ricochet, or Garrett's relay would have been off line or Hodges would have dropped the ball. But the play worked, and everybody believed.

The victory moved the third-place Mets from 1 1/2 games off the pace to second place, just a half-game back. They had won 18 of 25 games at that point, but the Wall Ball victory still left them with a losing record, 76-77. Clearly, the race wasn't a survival-of-the-fittest exercise. It was a contest to determine which team was least unfit. The Pirates' winning percentage was .500 at that point. The division leaders had been outscored through 150 games.

Numbers be damned, the Mets could read the signs. They understood the unseen hand seldom works its magic for teams destined for also-ran status, not in extra innings in a tight race in late September.

"You make a play like that in extra innings against the team you have to beat," McGraw said the following spring, "and you've got to believe. All that screaming I did didn't have the effect that one play had.

"I would have been shocked if we didn't win [the division championship] after pulling that one off and winning the game. The clubhouse was crazy afterward, like we'd clinched. That play changed everything."

"I guess it was a pretty big play," Hodges said years later. "The way things turned out, it was a really big game to win. You know [Ron] Swoboda always says, 'Some guys have a career ... I had a play [his diving catch in Game 4 of the 1969 World Series].' I guess it's pretty much like that for me, too."

And they believed.