This is arguably Dave Ballou's most "outside" recording to date. Its nine tracks are essentially one long free improvisation, with titles added later. At times it's unclear when one piece ends and the next begins; a quick check of the time display on your CD player is often the only way to tell. While this format may deter listeners unaccustomed to the aesthetic demands of free jazz, On This Day has much to offer adventurous ears. There's the lineup, for starters: Ballou on trumpet, Billy Drewes on soprano and alto saxes, Tony Malaby on tenor sax, Mike Formanek on bass, and Tom Rainey on drums. These highly esteemed players appear in constantly shifting combinations. They may goad one another to shrill heights of cacophony on one track, or pull back and plumb dark, mysterious corners of introspection on the next. Highlights include the disjointed tempo of the opening "Robin and Treebeard," Ballou's plunger effects on "Of Things Unseen," Rainey's strikingly unusual timbres on "Tangolina" and "PL," and the alto/trumpet/mallets interplay that introduces the closing "What Lies Ahead." Since there are no "compositions" per se and the playing is so entirely collaborative (with no conventional "solos"), On This Day probably isn't the best introduction to Ballou's work as a trumpeter and composer. However, for those who seek a highly challenging and unpredictable listen, the disc is well worth it.