We’ve been here before, Celtics fans, though it seems the view was never so dark, the future never so uncertain.

The cracks in the foundation started when Larry left last year. The long-anticipated retirement of Kevin McHale periodically caused the house on Causeway Street to rumble during this long season just ended. And the Chief, steady, implacable Robert Parish, had more than a few games when he looked every one of his 39 creaky years.

We knew a major renovation was in store if the House that Red Built was to regain its historic standing as the pride of the NBA neighborhood any time soon.

Then came Reggie.

Like a flood. Like an earthquake. Out of the blue and into the black…

The feeling two weeks ago was the Celtics could survive the loss of the Big Three because Reggie Lewis was there to build around for, oh, at least another 8-10 years. Boston might not challenge for the title for awhile, but the Celtics wouldn’t fall too far as long as their team captain was on the floor. And when management finally figured out a way to put a couple of good, young players next to Lewis, look out Knicks, Suns, and Bulls.

No question, Reggie has established himself over the last two seasons as one of the NBA elite. Night in and night out he got his 20 points, his five rebounds. When it came time to take a last shot, Lewis was the man you wanted to see with the ball in his hands.

How good did Reggie become?

So good he earned a spot in the mind’s eye as one of those rare NBA players who surprises the viewer more when he misses than when he makes a tough shot.

But that was two weeks ago.

Now?…

There is only the hope that the ugly-sounding heart condition Lewis has been diagnosed as having – ventricular tachycardia and focal cardiomyopathy – can somehow be controlled with medication, allowing Reggie to return to the court.

While it is premature to draw any conclusions about the likelihood of seeing Lewis wearing a Celtics No. 35 jersey again, it is natural to wonder.

What would we do in his position? Even if the medication worked, would we take the chance? Could we play with the same intensity if, somewhere buried in the back of our mind, there was worry about the reliability of the muscle that keeps us alive?

The rational part of the fan’s mind tells Lewis, “Don’t do it.” Don’t take the chance. Walk away glad to be alive. Be a good father and husband. Begin to shape a future without basketball, even at age 27.

It is the selfish part of the fan’s mind that can’t help but hope Lewis can somehow make it back.

If he doesn’t? What then for the Celtics, who will be without Reggie and McHale, and, possibly Robert Parish?

The parallels to past franchise personnel losses seem less applicable in these complex days of NBA salary caps, restricted free agents, and draft lotteries. There isn’t the feeling of optimism the Celts can rebuild like they did in the past.

After the 1968-69 title season, Boston lost franchise cornerstones Bill Russell and Sam Jones, who together had carried the team to nine NBA titles. It took five years, a relatively short time, before the franchise hung another championship banner. But the NBA was smaller then, and Boston had an all-star to build around in John Havlicek.

When Havlicek retired after the 1977-78 season, Boston plummeted in the standings the following season. This was the John Y. Brown period of ownership ineptitude, which resulted in Bob McAdoo arriving via trade.

But the down time was short-lived. Bird arrived for the 1979-80 season, bringing the good times back until Boston’s loss to the Lakers in the 1987 NBA Finals.

The decline has been gradual these past six seasons. At least, it has been until the last few days.

Now, it seems the house is falling down around the Celtics’ ears. Unfortunately, in today’s NBA, perhaps completely coming apart is the only way Boston will ever be able to rebuild.