Such innovations led directly to the profound symphonies of Gustav Mahler and Anton Bruckner, the brilliant operas and orchestral works of Richard Strauss — to name just a few important post-Wagnerians.

The influence has never abated. Baltimore-born composer Christopher Rouse's Ring-inspired "Der gerettete Alberich" will be performed during the BSO's Wagner program in April.

Out of his operas (he wrote his own librettos), Wagner achieved what was termed the Gesamtkunstwerk — total work or art, with music and drama fused in equal proportions.

To strengthen the structure of these "music dramas," Wagner employed the leitmotif, a theme that helps identify a character, an object, a feeling. This wasn't revolutionary in itself; other composers, notably Hector Berlioz, had explored the idea. But Wagner elevated the practice to a musically, theatrically, even psychologically complex art.

The Ring Cycle is the most audacious example of Wagner's aesthetic philosophy. It is not just monumental in scale, but also intimately involving; the mythic tale is filled with insights that bring the characters to our level, even as the music elevates them to rare heights.

The first act of "Walkure" that the BSO will perform — with tenor Brandon Javanovich as Siegmund, soprano Heidi Melton as Sieglinde, bass-baritone Eric Owens as Hunding — packs a tremendous amount of drama into a single, taut hour fueled by intensely expressive lyricism.

The last few minutes, when Siegmund and Sieglinde declare their love, deliver an ecstatic rush.

"That first act, more than any other act in opera, could be an opera in itself," Javanovich said, "the way it goes from such a low point, with Siegmund fleeing from his enemies, to this fabulous ecstasy. It's a journey of discovery."

Never mind that what Siegmund discovers is that Sieglinde is his sister. As the late comedienne Anna Russell famously said in the middle of her Ring analysis, "You can do anything in opera, as long as you sing it."

The power of Wagner's music is that it can persuade the listener even if the plot proves problematic.

"Wagner was able to paint a picture with a musical palette in a way unlike any other opera composer out there," Javanovich said. "It is just so sweeping in its entirety. Every note says something you can relate to in the story. You can't help but get caught up in the tsunami of sound."

King Ludwig II of Bavaria was so caught up upon discovering Wagner that he lavished money and affection on the composer in one of music history's most peculiar cases of patronage.

Such idolatry was a not uncommon reaction to Wagner in his day. But it required overlooking, or sharing, the composer's worst side.

In 1850, Wagner wrote a grotesque article, "Jewishness in Music," arguing that Jews were alien to Germany, were incapable of proper linguistic skills or producing anything but frivolous music, such as Felix Mendelssohn's. Wagner had the article republished less than 20 years later.

Hardly surprising that, long after his death in 1883, he would be embraced by the Nazis, or that he would posthumously provide a kind of soundtrack for the Third Reich.

"He can never escape that association," Alsop said.

It is Nazi association that has kept in place an unofficial ban on performing Wagner in Israel, despite efforts by some Jewish conductors, notably Daniel Barnenboim, to overturn it.

The fact there is also an Israel Wagner Society says a lot about the remarkable hold the composer continues to exert. (That society tried unsuccessfully last June to hold a Wagner concert conducted by Asher Fisch in Tel Aviv.)

The anti-Semitism issue is further complicated by Wagner's own behavior.

He penned his noxious article largely because he felt — wrongly, as it turns out — that the successful Jewish opera composer Giacomo Meyerbeer had conspired against him. But Wagner was favorably disposed toward another Jewish opera composer, Jacques Halevy.