There are rewards for doing almost every last thing right, and Sunday afternoon, Sarah Caldwell reaped them. When the final note was sung, and Turandot had yielded her melting heart to Prince Calaf, the venerable Opera House was the staging ground for a swell of bravas, cheers, stamping, and uproarious applauding. Even the critics - usually the first to dash away - could be seen standing to the last man and woman, applauding a bare stage.
And why not? Founder-artistic director Caldwell had brought Eva Marton in for a ''Turandot'' that was nearly picture-perfect. It wasn't just that she had that big, gorgeous voice at the center of things: It was that all the things themselves had been so meticulously looked after. From Ming Cho Lee's inspired sets to the sweeping use of supernumeraries, this production sparkled and sang with a clarity that belied the muddle and confusion that have characterized performances at the opera house in recent years.
It occurred to me, as I regaled myself in all this artistic exactitude, that we were seeing something more than craftsmanship at work here. The company seemed to have cut through the tangle of disasters that has plagued it for the two seasons I have been reviewing work here.
And I thought it not coincidental that, just recently, Sarah Caldwell announced that she was severing connections with the Marcos Regime in the Philippines.
In January 1982 Miss Caldwell had launched her company into an arrangement whereby she would establish an opera company in Manila, and the Philippine government would provide funds and personnel for her company.
The move proved to be a disaster for her and the Opera Company of Boston. Editorials were written, there were demonstrations in front of the theater, and everything she undertook was viewed through the shadow of her ''Manila connection.''
The issue was not a simple one for her to deal with. She needed money, and she defended her decision by pointing out that she was bringing something of value to the people of the Philippines.
Apparently, that argument fell apart, even for her, with the assination of Benigno S. Aquino. It wasn't long thereafter that Miss Caldwell's ''Manila connection'' began to quickly unravel.
I will be criticized, I'm sure, for drawing a connection between her decision and the artistic success of ''Turandot'' this weekend. But to me, the connection is inescapably there. And it bears a greatly overlooked lesson: Arts ventures, like any other human endeavor, are answerable to basic moral imperatives. It is impossible to achieve any genuine success while doing something that is at heart against your own principles and ideals.
An organization like the Boston Opera Company exists to further certain artistic ideals, to enrich and enliven the consciousness and conscience of a city and a country. Freedom of expression, the nobility of the individual, the rightness of human action - all are fundamental to what great opera is all about.
I find it difficult to believe that, at bottom, the people at Boston Opera ever really believed their ''Manila connection'' was in harmony with these principles. The moral confusion brought on by this dissonance of values had to show up in the company's work. And it did.
So did the converse. Caldwell and company sailed freely through a performance on Sunday that seemed to have the brisk winds of change behind it. There was more than artistry at work in that ''Turandot.'' There was moral force. Something that tends to reward itself.