Central to the profundity of 2001: A Space Odyssey is the notion that few things are more meaningful than a child's first steps, the emotive impact of this scenario manifest in every one of the film's dizzying set pieces, albeit multiplied to epic proportions. At its core, the film is a journey, a summarization of those questions that are both the simplest in their inquisition and most profound in their answers: Who are we, where do we come from, and where are we going? The film exists as an exploration of these timeless themes and the existential weight that accompanies them, probing our growth from passive eating machines subject to the unforgiving elements, to conquerors of the world and pioneers of space, awaiting only a helping hand from a superior force to reach the next level of existence. Just as the ape-men in the opening act must learn to use the tools around them to survive, so, too, must man learn to walk again when subjected to zero gravity, captured here with a gravitas that suggests a celestial being waxing philosophical.
The first step toward the stars comes when mankind, presented as the aforementioned ape-men roaming the Earth millions of years ago, realizes that a bone needn't be just a bone. This first (and simplest) tool gives way to an orbiting spacecraft in a ravishing and much-ballyhooed graphic match, then to the supercomputer HAL-9000 (voiced by the inimitable Douglas Rain), who—during the film's most plot-driven sequences—captures our ambitions and foibles as he inadvertently wreaks havoc on the central mission to Jupiter. The human performances in the film have often come under attack for their proposed woodenness; in actuality they succeed in capturing an archetypal timelessness via their finely condensed formalism while also providing the level-headed antithesis to HAL's deranged subtleties. Ironically, it's HAL's disembodied voice that provides the film with its most immediately human element, his tragically flawed personality (essentially manifest of a critical programming error) providing an emotionally vulnerable counterpoint to the film's otherwise perfectionist, externalized perspective. His breakdown is one of sentient self-defense, his eerie, predatory malice subtly foreshadowed by the much-feared predators of the ape-men in the first act. Once again, man must come to a new level of control over his environment if he's to survive, with Dave Bowman's (Keir Dullea) decisive disconnection of HAL—cold, collected, and emotionless—echoing the ape-men's newfound barbarity four million years prior.
Stanley Kubrick, like many great artists, often took to examining humanity from the outside in, a quality that both fans and detractors have mistaken for outright cynicism. 2001 is an incontrovertible counterargument to such misanthropic claims, both celestial and appropriately humble in its framing of our existence against the reaches of space, the semi-detached tone critical to its aura. Though God is never explicitly invoked in the film (Kubrick himself was something of a spiritual secularist), the unseen extraterrestrial forces—represented by the black, geometrical monoliths that appear at critical points throughout—are undoubtedly manifest of the God concept, and ultimately build on the notion. As a metaphor, the monolith is many things: an evolutionary trigger, a burglar alarm set to notify our having reached the next stepping stone, a porthole that penetrates the very fabric of space and time. It's no coincidence that the towering figures bear the likeness of a doorway, in the final act sending Dave beyond the infinite of space only to return him back to Earth, born again. The psychedelic sequence that accompanies the former is one of the preeminent accomplishments in all of film—a climactic, orgiastic sequence of alien landscapes, exploding nebulae, and wafting tides of organic space that practically leaps off the screen. Putting to shame the comparatively shallow thrills of virtually every blockbuster ever made, it may be the ultimate example of mind-blowing cinema; show us your O face, baby, and prepare to meet your maker.
This, however, isn't until long after the film has lulled the subconscious into a state of deep tranquility—essentially, a return to nature, of inwardness and meditation unhindered by the distractions of the rat race. Detractors often cite the film's lack of dialogue as a source of extreme boredom, but it's through the film's silent, deliberate hypnosis that it achieves its ballet-like majesty, with every painterly image and effortless pan and cut communicating not only a necessary narrative/emotional cue, but the wordless beauty of mankind as a creative, conscious entity at work in the universe. This sense of awe is appropriately complemented by the marriage of Kubrick's work with that of composers past, the thunderous notes of "Also Spake Zarathustra" catapulting man into the cosmos only for Strauss's "The Blue Danube" to titillate his senses once there. The space-docking sequences employing the latter evoke a range of feeling far beyond the evocative ability of language's too-literal limitations, at once exhilarating and bemusing in their waltz-like bliss, while the repeated use of the former marks mankind's many ascensions throughout the film. Their rhapsody is apparent throughout the entirety of the film, as individual moments made eternal, as literature created in the flesh. The final passages are the most exultant in their taking us beyond ourselves into a wide-eyed state of untarnished possibilities; entirely without words, the film reminds us that, despite how far we've come, the real odyssey has only just begun.