Being an adult is hard for many reasons, one being that the older you get, the more you learn how to hurt people. Not the flailing, impulsive kind of hurt, but the surgical kind, the tactical kind. It becomes harder to trust people. You dig for motives, wonder what others want from you.

Children aren't like that because they don't have the experience of being manipulated by those close to them--or, at least, they don't understand the mechanics of manipulation. Friendships can form for inscrutable reasons because the pleasure is in the camaraderie, not in what the friendship represents or how it aligns with certain ideas of what friendship should be.

This contrast drives Little Men, the new film from the writer and director Ira Sachs, and it's the wedge that pushes the titular friends, Jake (Theo Taplitz) and Tony (Michael Barbieri), from each other and their families.

The two meet just before high school, after Jake's family moves into a Brooklyn apartment left by his recently deceased grandfather, Max. Tony's mother, Leonor (Paulina Garcia), owns a clothing boutique just below the apartment and struggles to turn a profit, kept afloat only by the below-market rents Max charged.

Under pressure from his sister, Jake's father, Brian (Greg Kinnear), and mother, Kathy (Jennifer Ehle), demand that Leonor pay a higher rent, which Leonor insists will run her out of business. The conflict--a misalignment of incentives, desires, and concerns--simmers until it reaches its inevitable conclusion. It is all the more pathetic and painful for the passive aggression the three use to maintain the appearance of civility.

Jake and Tony are not bound by such false niceties. They are near opposites (Tony is lively and Jake is timid), but their friendship is the sort of strange paradox only children accept without question. They are honest and intimate, but ask little of each other. The essence of their friendship becomes clear when Sachs periodically cues the film's musical theme and simply observes. In the absence of audible dialogue, we see the inverse of the film's central conflict: companionship for its own sake, without terms and conditions.

This is the thing that fascinates Sachs, the blissful ignorance of childhood and the blind faith children place in instinct. He is interested less in how these phenomena work than in the miracle of their existence, and, if you are one to experience a film on thematic terms, you could read this as an elegy to that faith, to the way it is slowly pushed aside by awareness and experience.

But I don't believe Sachs thinks that way. He is not without opinions, but he does not use his films to evangelize. He is drawn toward the mysteries of the human heart, and is comfortable in the presence of mystery. He seeks understanding, not answers.

Faces are the key to this mystery, the ways they reveal, obscure, and lie, and Sachs has a way of making the space around his characters small to direct your attention to them. One of the film's key scenes is set in a small backyard, as two characters see who can inflict more emotional damage on the other. As Sachs stages this confrontation, it is not a war of words but expression, each character trying to keep the other guessing as everything around them falls out of focus. The words hurt, but neither side is willing to show it. They take blows and plan their next attack simultaneously.

You can tell faces are important to Sachs because he casts actors who are expressive but ambiguous, who can send conflicting signals. Kinnear, Ehle, and Garcia are masters of misdirection. The weight of responsibility hangs on them, but so do the rules of social decorum.

Taplitz and Barbieri, each making his feature film debut, are less mannered but, at times, similarly opaque. Taplitz--playing the introverted Jake--is keen and observant, though deeply guarded, while Barbieri balances Tony's brash affect with a sensitivity that's more than an ornamental display of complexity. Their performances are free of the sort of stilted, isolated line readings we expect from young actors. They trust their instincts.

This is important to a filmmaker prone to quiet observation. Sachs is not one to draw attention to his technique. For him, observation is not an aesthetic, but a way toward understanding. Though he arrives with general ideas about how people act and develop, Sachs does not etch them in stone, he does not prescribe. That's a tremendous balance to strike: to watch without judging, to empathize without preaching. But that balance is sort of the point. You can't engage with mystery if you think you know the answers.

Sachs pulls off another neat trick, building a story that could more easily be tethered to theme through interlocking webs of cause and effect. Small decisions ripple outward--as Brian, Kathy, and Leonor spar over matters of finance, their children become collateral damage. Jake and Tony realize this and respond in kind, sending a shock back through the chain of command.

But it is not so simple as a battle between innocence and cynicism. Each push and pull leaves an unintended cloud of debris, and the dust never quite settles. By doing what seems right in the long term, each side makes the short term more difficult, and changes the rules of engagement.

These sorts of webs lend themselves to heightened melodrama, but Sachs is not one for theatrics. Even as pressure builds and tightens, he leaves room for quiet, softness, space. Things get messy, but they are rarely loud, and because of that, they hurt more. You can make the case that someone in hysterics is not "being himself." Not so when he keeps an even temper. To hurt someone loudly, you just have to feel. To hurt someone quietly, you have to think.

If there's an argument Sachs makes here, it's for empathy. He presents characters with conflicting interests and shows you what happens when they remain blinded by limited perspectives. Near the film's end, Brian admits to Jake that he wishes he'd handled his conflict with Leonor differently. Jake asks if this would have changed the outcome. Probably not, Brian admits, but he understands that big moments are made of smaller moments that matter for the ways they make you feel, how they can make your day just a little better, or a little worse.

Sachs is not a moralist, but he's willing to listen and learn, and to admit that a just process may not always yield better results than a broken one. In a cultural climate still adjusting to the Internet's media revolution--and the openings it created to entrench yourself in communities that confirm your biases--that's a radical move, and one that bears repeating.