“The horror! The horror!” The terminal valediction of Kurtz in Joseph Conrad’s “Heart of Darkness” is deconstructed with a raging eloquence in Colombian director Ciro Guerra’s majestic, spellbinding film, “Embrace of the Serpent.” Is the unspeakable savagery evoked by his dying words really beyond the reach of the civilized imagination? I doubt it.

That tricky word “civilized” connotes enlightenment, behavioral restraint, evolutionary advancement and the suppression of bestial impulses. But what is so civilized about mass slaughter, torture and planetary despoliation in the name of anything or anybody? It shouldn’t have taken a journey up the Congo River for a white man to discover the evil within.

That is the uncomfortable truth at the core of Guerra’s tragic cinematic elegy for vanished indigenous civilizations in the Amazon jungle.

Viewed largely through the aggrieved eyes of a shaman whose tribe is on the verge of extinction at the hands of Colombian rubber barons in the 19th and 20th centuries, “Embrace of the Serpent,” a fantastical mixture of myth and historical reality, shatters lingering illusions of first-world culture as more advanced than any other, except technologically.

The director’s third film, it is the more remarkable for being shot in black and white, with one brief color sequence near the end. “Beautiful” isn’t a strong enough word to describe its scenes of the heaving waters of the Amazon and its tributaries, on which two explorers, separated by more than 30 years, navigate in canoes, accompanied by the shaman, Karamakate.

The film’s central figure, he is the last survivor of the Cohiuano, an Amazonian tribe killed off by the rubber barons. He is no innocent, noble savage, but an angry, morally complex individual with a heart full of grief. He may be in greater harmony with the natural world than any foreign intruder, but he is alone. The film gives full voice to his view of a social order in which the rules of nature assimilated and handed down through the centuries among the Cohiuano must be obeyed, or else.

The Amazonian ecosystem, in which everything seemingly preys on everything else, is a continual and endless feeding frenzy. In a signature image, an aquatic serpent devouring another snake is observed by a glowering leopard.

Inspired by the travel journals of Theodor Koch-Gruenberg, aka Theo (Jan Bijvoet), a German ethnologist and explorer, and Richard Evans Schultes, aka Evan (Brionne Davis), an American biologist considered the father of modern ethnobotany, the film imagines their parallel journeys, decades apart, seeking the “yakruna,” a sacred healing plant. This miraculous cure-all is a hallucinogen that attaches itself to rubber trees.

In Karamakate’s eyes, the European and American marauders who enslaved and destroyed his tribe are agents of an insane culture devoted to genocidal conquest and rapacious destruction. He finds the concept of money laughable; it is just useless paper. He urges the explorers to throw their luggage overboard. Their possessions are “just things,” he scoffs. To the extent that the film persuades you that he is right, “Embrace of the Serpent” is potentially life-changing. One thing Evan refuses to relinquish is a portable phonograph on which he plays a recording of Haydn’s “Creation.” Karamakate responds respectfully to the sublime music.

The first journey takes place in 1909, when Theo is near death. (Koch-Gruenberg actually died in 1924). Accompanied by the young Karamakate (Nilbio Torres), he is escorted by canoe up the Amazon River with a guide, Manduca (Yauenku Miguee), who had worked on a rubber plantation and was freed by Theo. In a movie in which nine languages are spoken, Manduca is the cultural mediator and sometime interpreter. Initially reluctant to help Theo find a yakruna, Karamakate agrees to help only if Theo will help him locate other surviving members of the Cohiuano, who he says exist.

Later, Evan makes the same journey with the older, enfeebled Karamakate (Antonio Bolivar Salvador), whose tribe is now extinct. Karamakate has lost his ability to communicate with rocks and trees and is weighed down by a resigned sadness. The movie jumps between the two journeys, which follow roughly identical routes.

The film’s anger is concentrated in two devastating scenes of tyrannical white intruders. At a Roman Catholic mission, a Spanish priest presides over a flock of boys orphaned by the conflicts between rubber barons and indigenous tribes. Dressed in white robes and forbidden to speak “pagan languages,” the boys are viciously whipped at the whim of this Dickensian monster.

Decades hence, at another riverside community, the dying indigenous wife of a self-proclaimed white messiah is healed by one of Karamakate’s potions, and her husband proclaims himself the Son of God. In a delirium, he invites his followers to consume his body and blood. As they encircle him like vultures, the visitors flee.

From here, the film moves to mystical higher ground, as abhorrence expands into awe. Instead of “The horror!,” I would substitute “The wonder!”

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An Oscar nominee for best foreign language film. In Spanish and Amazonian tribal languages, with English subtitles.