In the beginning, Wayne Cashman rapped a rebound past Billy Smith and Peter McNab scored from the slot and the Boston Bruins led the New York Islanders, 2-0, and the Gallery Gods saw that it was good.

But in the second and third periods, New York notched four straight goals and deposited the Bruins in the void of elimination. Now the Bruins can rest until next season, and the Islanders, by virtue of their 4-2 victory last night at Boston Garden, advance to the NHL semifinals after capturing the best-of-seven quarterfinals, four games to one.

Trailing by two goals only 3:28 into the contest, New York stifled the born again Bruins the rest of the way by slowing the pace of the game and frustrating their offensive thrusts with stiff backchecking.

The genesis of the Islander comeback was a slapshot by Stefan Persson at 17:23 of the second period which weaved through a tangle of players and found its way into the Boston goal.

Duane Sutter beat Boston goalie Gerry Cheevers low to the stick side to knot the score at 2-2 early in the final period, and Clark Gillies, no Garden favorite, added the decisive tally with 14:02 left in regulation.

Forechecking by linemates Goring and Sutter set the goal up, with Gillies writing the puck past Cheevers' left shoulder from 30 feet out to give the Islanders their first lead.

With the Bruins nervously tapping their sticks and the crowd squirming, Islander defenseman Denis Potvin cushioned New York's lead and dispelled hopes of a replay of Monday night's last-minute Boston heroics. "Denny All-Star," as he is sometimes known among Islander cognoscenti, pulled in a centering pass from Mike Bossy and connected for his first post-season goal at 14:27.

Several Smith saves, two brawls in the stands and a few half-hearted chants of "New York Sueks" later, the apocalypse had arrived and the Gallery Gods began packing up for the gloomy exodus to the Green Line hulks waiting outside.