If one needed further proof of the contemporary revival/reassessment of the ambitiously overwrought sensibilities once so reviled in 70's rock, this aggressively mind-bending second album by The Mars Volta offers it up in spades. Band mainstays Omar Rodriguez-Lopez and Cedric Baxter-Zavala insist that labels like "prog" don't interest them, and that this is emphatically not a "sequel" to 2003's De-Loused in the Comatorium. What it is was thematically inspired by a stranger's diary allegedly found by late bandmate Jeremy Ward, the basis for an expansive, often amorphous musical head-trip that brews psychedelia, trance, hard-rock and free-jazz into a daunting new whole. The dozen tracks here represent but five "songs" proper, though the band's disdain for conventional track banding inspire it to sound more like a stream-of-consciousness soundscape from Can--or a dark, lyrically inventive, if decidedly troubled corner of their ids. On the "Umbilical Syllables" portion of "Cygnus.." and "The Widow" Bixter-Zavala invokes the wailing, Zeppelin II & III spirit of Robert Plant set against a feverish, swirling melange that's anything but the blues. The vocalist coaxes "L' Via l'Viaquez" en Espanol, while his band indulges its space-mambo conceits with an evocative spirit that recalls Latin Playboys at their most mischievous. It's an album that loops back on itself in a haunting ellipse--and one whose boundless ambition makes Pink Floyd sound like three-chord bar punters by comparison. --Jerry McCulley