When Caetano Veloso sings, it sounds more powerful than reality, but he knows it’s real. For all of the whimsy, beatitude and hallucinogenic sensuality in his music, the colossal Brazilian songwriter has always been an artful pragmatist, a devout atheist and an unwavering skeptic of the hippie-dipped mysticism that fogged the dawn of his recording career way back in 1967. It’s made him unsolvable and eternal. We’ll never be able to touch the music falling from Veloso’s lips, but we can still believe in it.

Now, Veloso is 76 years old, which puts him more than 50 years past the invention of tropicalia, a worldly dialect of pop that, once upon a time, opposed Brazil’s brutal military dictatorship with style and courage. In Veloso’s poetic 1997 memoir, “Tropical Truth,” he describes tropicalia as a music “made of happenstance and misunderstandings” designed to “destroy the Brazil of the nationalists.” And with that specific goal in mind, Veloso and his fellow tropicalistas absorbed influences from near and far — the proud sophistication of bossa nova, the melodic idealism of the Beatles, the clever cool of Andy Warhol and more.

But if there’s a central life force residing in the heart of tropicalia — then, now or tomorrow — it’s the music’s radical, radiant optimism. For Veloso, making music in the late ’60s was “the right to imagine an ambitious intervention in the future of the world, a right that immediately begins to be lived as duty.”

And the future is here (at least for now). Brazil has elected a far-right president and Veloso is touring the planet again, accompanied by his sons, Moreno, Zeca and Tom, three young vocalists who have clearly inherited their father’s sly, devastating tenderness. Performing at the Music Center at Strathmore in North Bethesda, Md., on Monday evening, the smiling patriarch described the concert as a “celebration of reproduction” — a good joke that could also be applied to the eternal springiness of hope itself.

Veloso knows plenty about propagating optimism in heavy times. Tropicalia was in full bloom in December 1969 when Veloso and his songwriting comrade, Gilberto Gil, were arrested without explanation, imprisoned for months, later put on house arrest and eventually exiled to London. They returned a few years later as national heroes, but the trauma cemented Veloso’s commitment to a democratic Brazil — a vow he renewed in an October op-ed he penned for the New York Times on the eve of Jair Bolsonaro’s election: “I was forced into exile once. It won’t happen again. I want my music, my presence, to be a permanent resistance to whatever anti-democratic feature may come out of a probable Bolsonaro government.”

Politics weren’t mentioned explicitly during Monday night’s concert, but if Veloso’s long-term proposition involves waving off the iron fist of authoritarianism with harmonies of every color, he was obviously carrying out his life’s work onstage, filling the air with shimmering pleasure, and a latent suggestion of dread, too. All the brightness in the room meant it was very dark outside.

The show began with two flashes — one tune famously recorded before Veloso’s exile and one after. The first was “Baby,” a ballad that embodied tropicalia’s hybridized aesthetic with a dash of English (“Baby, I love you”) and a seemingly bottomless voluptuousness. After that, “O Seu Amor,” a song penned by Gil that allowed father and sons to sing in telepathic, trapezoidal harmony — as if some impossible nano-breeze were suddenly swaying their DNA strands in perfect parallel.

From that point forward, everything felt astonishingly distinct, yet inexplicably vague. How could singing this pure, this concerted, this immediate still carry so much ambiguity?

When the quartet’s melodies slanted toward the solemn (during “Ofertório,” an ode written for Caetano’s mother on her 90th birthday), the Velosos seemed to be mourning a future that may never arrive. When they floated into more high-hearted spaces (during “O Leãozinho,” one of the greatest lullabies in the family songbook — or any songbook), you could see the four of them squinting off into utopia. Listening in both directions was almost enough to take you outside of yourself. But only almost. This was happening.

Perhaps to prove it, Caetano leaped up from his chair late in the program and moved toward the edge of the stage, eager to shake out his limbs. He had just spent the past hour or so levitating through all of that lush genetic harmony, wise and weightless. Now he was dancing to the music of his children — feet still touching the ground, stepping into a future that can still be changed.