There has hardly been a composer who didn't disown some of his works. Some, like Johannes Brahms, simply destroyed the unworthy pieces and leave posterity to wonder what treasures might have been lost to painstaking perfectionism. Others, not finding it within themselves to physically obliterate what they toiled so hard to produce, bury the offending manuscripts in their personal libraries or attics, leaving open the possibility that someday the "lost" may be found. Anton Webern was of the second type -- dozens and dozens of previously unknown works by him trickled onto the field in the decades following his death in 1945, some early student works, some finished mature compositions that never saw the light of day, and some pieces caught halfway between draft and finished product. His Opus 1, the Passacaglia for orchestra is, as is known well today, hardly his first effort at the craft; many, many pieces predate it. The label Opus 1 is thus a touch misleading: the Passacaglia is not so much the beginning of Webern's journey as it is the first waystation at which he stopped to say, "aha -- here we have something." Each of the pieces that preceded it is to some degree irreparably flawed, technically and often aesthetically; by contrast, the Passacaglia is the first piece that might truly and proudly be reckoned a "Webern" -- hence, Opus 1.
The Passacaglia dates from spring 1908, a time during which its composer was caught in an uncomfortable limbo between student life and life as a professional conductor; Webern found his first real job, assistant conductor and chorus coach at the theater of the posh resort town of Bad Ischl, during the summer of 1908. His first conducting experiences were not apparently everything Webern had hoped them to be, but he remained relatively undaunted, and in November conducted the premiere of the Passacaglia back in Vienna. The piece was and would always remain the most welcome of Webern's works so far as concert promoters and ticket sellers were concerned, and in 1918, partly as a response to the work's relative popularity, Webern made a version for piano six-hands (yes, six, not four!); this arrangement has since, however, been lost.
Opus 1 is a proper passacaglia; it has an eight-bar ground bass in D minor, which is repeated over and over again as new music unfolds around it. The individual "variations" are not explicitly identified and marked as such, but for most of the piece they are simple enough to follow, even after Webern surrounds the ground bass with chromatic gusts and torrents that put a real strain on D minor and tosses the ground bass out of the actual bass up into the upper voices. A great deal of the latter portion of Webern's Passacaglia is, however, more freely composed; here the eight-bar theme disappears for large spans, and the rigid, repetitive structure is disguised as music that sounds, curiously, a little like a sonata-form development and recapitulation.