It is a discouraging sign of the musical times, but right now there are probably only three conductors who are genuinely equipped to give us great performances of Wagner's 18-hour "The Ring of the Nibelungen." One of them is Erich Leinsdorf, and in his concert with the Cleveland Orchestra last night at the Kennedy Center he demonstrated the true magnitude of "The Ring" at its grandest moments.

Last night's music was from the late parts, opening with something unconventional from "Siegfried" and then going on to "Go tterda mmerung": the Rhine Journey, Siegfried's Funeral Music and then the epilogue of the last act. Sure, "The Ring" is a little out of fashion right now, and given the grim possibilities for adequate casting, this may at times be a blessing in disguise. But one thing that makes one less than optimistic is that the other two unquestionable masters of "The Ring," Karajan and Solti, are both roughly the age of Leinsdorf, who just turned 70.

Even under modest circumstances, though, the high points of "The Ring" have incredible power. If anyone could get through last night's playing of the Funeral Music -- one of the really magnificent moments in all of opera -- and claim to be unmoved, it would raise real questions about that listener's basal metabolism.

"The Ring" is harder than even lots of other Wagner because it can be diffuse and because the overall shaping of it must be on so large a scale and in such an immense time frame. And you don't get a fine "Ring" from an orchestra that doesn't already know it well, and isn't accustomed to its astonishing difficulties. In other words, no one--not even a great orchestra--could sight-read it. A conductor can master its pitfalls only by much study and experience.

Just two examples from last night: the way the Cleveland played the low brass passage, which often gets lost, just before the Siegfried leitmotif shoots out in the solo trumpet for the first time; the control of Leinsdorf's crescendo beginning with Daybreak. These sound like small details, but they are just the opposite in music of this breadth.

It has to be noted that before the Wagner, Andre' Watts played two major Liszt works. His playing of the Second Concerto was extraordinary. Like many a former prodigy, Watts has continued to be characterized as "talented" long after something stronger was needed. He now has an awesome mastery of the keyboard, technically and interpretively. He also played the threadbare "Totentanz" extremely well.

Leinsdorf led Mozart's "Linz" symphony with much precision and not much feeling.