Even in a time when new movies are produced faster than the public can devour them, it would be impossible for a film like Boyhood to pass by unnoticed. In 2002, director Richard Linklater audaciously began a project that would last the next 12 years, filming with the same cast and crew for a few weeks each summer. Linklater chose 6-year-old Ellar Coltrane to play his main character, Mason, with only a loose idea of his evolution in the film and no concept of how he would develop offscreen. Linklater’s daughter, Lorelei, plays Mason’s sister (Samantha), and Ethan Hawke and Patricia Arquette are their divorced parents (Mason Sr. and Olivia). In essence, the resulting story is of a boy growing up, but more than that, the film is a lens through which we can view our own complex lives.

In a cinematic world of elaborate, intricate plots and exaggeratedly quirky characters, Boyhood is an outlier — instead of a traditional plot arc, it is one continuous narrative where all the scenes feel equally important (or unimportant). The intrigue is the narrative’s universality; the characters are notable for their natural human complexities rather than contrived idiosyncrasies. This realness is largely what makes Boyhood great.

Throughout the film, Mason grows from an imaginative, sensitive kid — his teacher tells Olivia that he spends his time “staring out the window all day” — into an introverted, thoughtful and inquisitive young man, who is often skeptical of the world around him. Over the years, we see him play video games with his stepbrother, watch porn for the first time, and navigate his way though crushes and relationships. We see Mason turn away, embarrassed, from his mom’s attempt to kiss him goodbye at school. As his hair changes style and his voice changes timbre, he feels his way through adolescence and begins to explore his artistic interests, simultaneously trying to find footing in both his own world and society.

It’s not just Mason who grows up. Olivia goes from a struggling single parent to a successful, if not entirely satisfied, college professor (“I’ve spent the first half of my life acquiring all this crap, and now I’m going to spend the second half of my life getting rid of all this stuff”). As Mason Sr. becomes more present in his children’s lives, we witness his initial insecurities about being the less-involved parent. In one scene, he pulls off the road to criticize Samantha for not answering his questions about her week. When she tells him why she couldn’t describe her art project — “It’s abstract!” — he agrees to let the conversation flow more naturally. Ultimately, when he settles down with a new wife and baby, he also seems more settled in his role as Mason and Samantha’s dad.

The scenes Linklater show us are clips of life, snippets of conversation, slices of childhood and adolescence. Instead of weddings, birthday parties and divorces, we see Mason’s elementary school teacher tell him to stop playing computer games so he can finish a project. Mason’s grandmother says he’s had enough chocolate. He’s called a “pretty boy” in the middle school bathroom for looking in the mirror to arrange his hair. Most of these scenes wouldn’t be particularly striking if they were viewed individually. But as the film progresses, the moments layer themselves, connecting in subtle and unexpected ways, and we begin to see Mason as the sum of these parts.

Many of these moments are important and meaningful, but they aren’t milestones in a traditional sense. We know milestones as familiar, almost predetermined points in a life, significant or important events that measure change over time: marriage, divorce, the birth of a child. According to the Oxford English Dictionary, however, a “milestone” was originally a stone set up on the side of a road “indicating the distance in miles from that point to a particular place.” That a milestone measures the distance to, not from, somewhere says something about how we live: waiting for the next big event, life change or birthday to remind us how much (or how little) time we have left.

In Boyhood, Olivia expresses, or realizes, this only as Mason is leaving for college, in what is perhaps the film’s climactic scene, if there is one. In a moment of profundity, she says through tears, “I just thought there would be more.” In one light, this is a mother swept up in the emotions of her youngest child leaving home, though it also points to one of the most real and immediate messages of Boyhood: there is more.

In one sense, Boyhood is about growing up. It’s about family relationships and romantic ones, about how we cope with everything life sends our way. But, in a larger sense, it’s about the sum of life’s infinite parts. It’s about the ways that endless daily vignettes — the “more” that Olivia seems to search for — add up, come together and build upon one another to shape who we are.

In the final scene, Nicole, a girl Mason meets on the first day of college, wonders if life is less about seizing the moment than the moment seizing you. This might be the film’s most significant message. To watch the moment seize Mason for his entire life and ultimately see him turn out okay speaks volumes to the notion that we are built gradually, piece-by-piece and layer-by-layer — that marriages and divorces, an inconsistent home life or being rejected from a dream school aren’t the parts of life that define us. If milestones are just an outline, it’s moments that fill the empty space.