The phrase "American primitive guitar" is either highly evocative or utterly confusing when first encountered. What it ultimately means, though, is a guitar technique based on the kind of finger-picked playing one hears on certain blues, jazz and country records of the 1920s and '30s. The style in its contemporary incarnation features slowly evolving, repeated patterns of rhythm and melody played in counterpoint on the bass and high strings. It requires high-precision finger work and can either be delicately beautiful or heavily dissonant in its evocations of mood.

The patterns of repetition are not dissimilar to those such minimalist composers as Philip Glass and Steve Reich brought to modern classical music in the 1970s and '80s, but do not drone on for so long, often breaking into a spontaneous melodic pattern.

The style has its beginnings with John Fahey and a small group of like-minded artists who began recording ragtime-influenced, steel-guitar folk in the late 1950s and early 1960s. Fahey founded the Takoma record label to spotlight these artists and introduced the world to both Leo Kottke and Robbie Basho via their first recordings. Kottke, of course, is now the world famous founder of his own brand of machine-gun precision folk guitar. Basho enjoyed neither the commercial success of Kottke nor the mythic adulation of Fahey, but his incorporation of Eastern rhythms and mysticism into his own playing was highly influential: his best-known student, Will Ackerman, added electronic atmospherics to his own brand of American primitivism. Following Fahey's example, Ackerman founded his own record label, Windham Hill, to spotlight his and like-minded instrumentalist's new direction, setting off what became (for better or worse) the new age musical movement of the 1980s.

Between 2005 and 2008, Tompkins Square Records released three collections of American primitive guitar music, each titled Imaginational Anthem. Now collected together in a bargain-priced three-CD box set, Imaginational Anthem, Vols. 1-3 should be considered the definitive primer of the genre. This collection does an admirable job of bridging past and present, mixing contemporary artists and performances with classic tracks from early proponents of the style, and in doing so demonstrates its timelessness.

With the exception Kottke, nearly every prominent figure of the American Primitive revival of the 1960s-'70s appears here. The collection features Harry Taussig's "Dorian Sonata," from his lone and long out-of-print 1965 album Fate is Only Once. Robbie Basho is included via a live version of "Kowaka d'Amour," which originally appeared on his bizarre and brilliant 1969 album Venus in Cancer. Suni McGrath -- a student of the Rev. Gary Davis and Mississippi John Hurt, who released three albums between 1969 and 1972 -- is represented by the light, bright "Train Z." Peter Lang's "Future Shot at the Rainbow," originally released in 1972 but re-recorded for this anthology, offers a galloping and chiming 12 minutes that presents a good choice to play as an introductory cut for a novice listener. And Sandy Bull's untitled contribution resonates with a delicate beauty made somber with the knowledge of the drug addiction that cut his recording career short.

The contemporary players here serve the genre well while intimating possible directions for the future. Brad Barr's "Bouba's Bounce" mixes flamenco-like flourishes with darker, lower tones. Richard Crandell's "Zocallo," with its Bach-like tonal structure, is reminiscent of Will Ackerman's playing, but less ponderous. Greg Davis adds electronic drones and distortion to his "Sleep Architecture" and in doing so invokes comparisons to the "apocalyptic folk" subgenre populated by the likes of Current 93 and Nurse With Wound. Only one artist appears twice here (if you don't count two versions of Max Ochs' "Imaginational Anthem" which gives the collection its name) and that is Jack Rose, the brilliant and adventurous young Philadelphia-based guitarist who died suddenly of a heart attack in December 2009. His contributions should inspire a further investigation into his too-brief recording career.

Another element worthy of high praise for this collection is in how it provides a spotlight on women artists. Too often, guitar wizardry is seen as a boy's game, but excellent selections by Janet Smith, Kaki King, Sharron Krauss and Christina Carter demonstrate that, while women may be outnumbered in this genre, they are not outplayed.

So expansive a collection of such a deliberately narrow musical form can't help but strike a few sour notes, of course. But to my ears, there are only a couple cuts that had me pondering the question: "Avant-garde masterpiece or guitar-tuning exercise?" For most listeners, these three-plus hours of music might serve as peaceful background music for life's other activities, and that's a fine use of this fine collection. But know that this is a collection that rewards closer listening as well, for the level of artistry and the finger-bending complexity of many of these cuts is astonishing, even, sometimes to the players themselves. When Robbie Basho exclaims "I did it!" at the conclusion of his 10-minute performance of "Kowaka d'Amour," his giddy sense of disbelief in his own accomplishment is infectious and amplifies the sense of awe that this song and so many others here can inspire.