“A Tale of Love and Darkness,” Natalie Portman’s directing debut, addresses a hugely complicated and consequential moment in 20th-century history: the founding of the state of Israel. There is no simple way to tell the story, and Ms. Portman’s film, closely based on a memoir by the Israeli novelist Amos Oz, is full of mixed emotions and chronological tangles. But despite the geopolitical momentousness — and present-day potency — of its concerns, it’s an elegant and intimate movie, a thing of nostalgic whispers and sighs rather than polemical slogans and shouts.

In more ways than one, it’s also an intensely literary film, preoccupied with language — Hebrew, which Ms. Portman speaks fluently — and preferring nuances of mood and memory to details of plot. Before he was the acclaimed writer Amos Oz, the narrator and protagonist was Amos Klausner, born in Jerusalem in 1939 to parents who had escaped the accelerating horror of Europe. In the years following the climax of that horror, family members find themselves caught up in the conflict, confusion and excitement leading to the end of the British mandate and Israel’s war of independence.

Torn between pride and skepticism, idealism and disappointment, they are at once actors in a sweeping international story and guinea pigs in a risky political experiment. Amos (Amir Tessler) is an alert and watchful child, and the entwined dramas of Zionism and his parents’ marriage are filtered through his quizzical consciousness.

Amos’s mother, Fania (Ms. Portman), is bookish and melancholy, haunted (at least in her son’s recollection) by memories of her home in Ukraine and plagued by headaches and other ailments. The boy’s interpretation of his mother’s condition — offered by his older self (Moni Moshonov), who serves less as narrator than interpreter of his childhood — is that her romantic European temperament was unsuited to the hard realities of the Middle Eastern desert. The world she left behind is imagined as a lush, shadowed, fairy-tale environment, a stark contrast to the dry, sun-bleached reality of a fledgling modern nation. Her death, announced at the outset, is the film’s central obsessive, unsolvable mystery.

Fania’s childhood image of Israel was of a muscular pioneer (Tomer Kapon) — a soldier or a farmer, depending on the particular fantasy. She ended up instead with a Lithuanian-born literary critic, Arieh (Gilad Kahana), whose nerdiness verges on caricature. “You’ll be bullied in school,” he tells his son. “But not because you’re Jewish.” And for him, that’s the essence of Zionism: not redemption or perfection, but normalcy.

What happens to Fania — again, as her son understands it — is an implicit critique of that idea. One theme of “A Tale of Love and Darkness” is that a dream come true is inevitably a disappointment, a notion that seems to allude to one of the foundational mottos of Zionism. “If you will it, it is no dream,” Theodor Herzl, an architect of modern Zionism, said, but Fania suffers precisely from an atrophy of will and an inability to dream.

That, at least, is the literary and ideological diagnosis that Ms. Portman teases out of the pages of Mr. Oz’s dense and sprawling book. On a more literal biographical level, Fania suffers from a psychological malaise exacerbated by the condescension of her in-laws (Arieh’s mother remarks that Fania’s borscht is “almost flavorful”) and her own mother’s cruelty. She suffers, perhaps a little too beautifully, like a heroine of melodrama. But that is partly how her son remembers her.

There are many lovely and memorable moments in this film, which is in every way the opposite of a vanity project. If anything, Ms. Portman seems constrained by her own modesty, by a justified but nonetheless limiting reverence for her source material.

“A Tale of Love and Darkness,” a conscientious adaptation of a difficult book, breathes a little more freely when it leaves the claustrophobia of the Klausner household and allows young Amos to confront the world outside his parents’ shadow. At those moments, often when Ms. Portman herself is offscreen, her directing also feels more open and self-confident, and you understand that in telling the story of how Mr. Oz developed his voice she has gone some distance toward discovering her own.

“A Tale of Love and Darkness” is rated PG-13 (Parents strongly cautioned). Love and darkness. It is in Hebrew, with English subtitles.Running time: 1 hour 38 minutes.