From the free-spirited abandon of Slacker and Dazed and Confused to the Oscar-nominated odyssey Boyhood, writer/director Richard Linklater has long been one of the most adventurous, thoughtful and innovative filmmakers in the world of independent cinema. His 2001 effort titled Waking Life is a shining illustration of his singular voice. It also contains many of the elements that have preoccupied him throughout his career; mainly in its use of non-actors, its exploration of complex themes like existentialism, and its boldly imagined challenge to traditional narrative form and structure.

The story - or what there is of it - concerns a young unnamed protagonist who questions the reality of his existence. Is he awake, or is he living an endless dream? This dilemma is compounded by the many peripheral characters he encounters along his journey, which are portrayed by the likes of actors Ethan Hawke and Julie Delpy, radio host Alex Jones, philosopher David Sosa, director Steven Soderbergh and Linklater himself. Each of them pontificates on the meaning of life, the expansion of consciousness and the notion of free will as the lead character stands mostly silent and listens attentively.

Some viewers may find this exercise ponderous and dull. But those attuned to its curious and searching tone will find much to relish. The story may be light in incident and action, but it's enormously rich in ideas.

Upon its release, Waking Life generated most of its press ink due to the style in which it was made. Linklater shot the film on digital video and then cut it together in a traditional editing suite. He then recruited a talented team of artists to paint over each individual frame in a unique process known as interpolated rotoscoping. This was a strange, outside-the-box approach, especially for a film that consisted largely of conversations and not otherworldly set pieces. The end result, though, is not only technically admirable, but organic to the thematic content of the film. It's like real life with a coating of the surreal.

Waking Life is an essential and challenging work in the career of one of our greatest cinematic artists.