Romantic love gets all the hearts on Valentine’s Day.

But for David Mancuso, it was all about love of music, dancing and community when he held a party with the theme “Love Saves the Day” on Feb. 14, 1970. Eventually known as the Loft, the weekly party was held in his own downtown loft at 647 Broadway. It was a nightlife movement that ushered in the first flips, dips and dizzying twirls of what would become the disco era.

Before legendary New York nightclubs such as Studio 54 and Paradise Garage, and before “Saturday Night Fever” burned up dance floors around the world, Mancuso kicked it all off with his “Love Saves the Day” party, which was more about fellowship than relationships.

“It was a spiritual experience,” says Daniel Walters of the Morrison Hotel Gallery in Soho, where the “Disco at 50” exhibit opens on Friday — 50 years after Mancuso opened up the doors of his home to a diverse group of party people for his private Valentine’s Day soiree. “David started throwing parties at his apartment to bring people together. It became this kind of commune.”

Six months after Woodstock said peace out to the ’60s, the hippie spirit of the Bethel, NY, festival got a Manhattan makeover in the downtown underground, as Mancuso — who would also DJ at his invite-only affairs — kept the counterculture groove going into the ’70s.

“His mind was more focused on universal love than a narrower idea of regular romantic love,” says Tim Lawrence, author of “Love Saves the Day: A History of American Dance Music Culture, 1970-1979,” who helped Mancuso bring the Loft parties to London in 2003. “He was a child of counterculture. He had gotten interested in the liberating potential of LSD and had spent time with Timothy Leary. He was partly interested in what would happen if you put some of the things that Leary was doing, but then you have a more diverse crowd in terms of sexuality and race.”

In fact, “Love Saves the Day” — the message on his homemade invitations — was a play on LSD. “[Mancuso’s] theory was, ‘Well, what if we take some acid and then instead of lying down on our backs and tripping, we actually move our bodies?’ ” says Lawrence. “And it turned into an extraordinarily joyous, compelling, creative event.”

Beginning simply as a house party, with Mancuso inviting his friends, the Loft brought the non-commercial vibe of the Harlem rent parties downtown. There was music, food and balloons, but nothing for sale — including alcohol, which wasn’t served. “There was a contribution at the door and that kind of covered it all,” says Walters.

By not selling any food or alcohol, Mancuso would be able to wiggle around cabaret-license laws and keep the party going after-hours, from Saturday night into Sunday morning. But even as word of the party spread, Mancuso wanted to keep it intimate. “You would let yourself go more if you were in an intimate, relaxed environment than if you were in a public setting,” says Lawrence. “He felt that if people were more comfortable, the party would be more dynamic, more interesting, more exploratory, more transcendental.”

In 1975, Mancuso — and the Loft — moved south to a larger space at 99 Prince St., before Soho was known as Soho. It was at this location that John “Jellybean” Benitez became one of the influential DJs who was inspired by the music and the message of the Loft.

“I’d never seen anything like it,” says Benitez, executive producer and host on SiriusXM’s Studio 54 Radio channel, who was about 18 when he started coming down from The Bronx to go to the Loft. “I learned from watching and listening and participating in that energy. David played a lot of songs I had never heard before, and I’d find myself searching for them when they were commercially available.”

Benitez, who spoke at Mancuso’s 2016 funeral, says that it was more about the programming of songs — from soul and funk to jazz and African music — than the synchronization of beats on the Loft’s killer sound system. “Sometimes there was space between the songs,” he says, “and the audience would just clap and stay on the dance floor. And then he’d play the next record.”

Cynthia Cherry went to the Gallery — a Manhattan club inspired by the Loft — before getting invited to 99 Prince St. by a friend in the mid-’70s. “It was everything,” says Cherry, who worked in dance music A&R. “There was a sense of freedom and togetherness, unity. It was like church. You could see people dancing off their worries, swerving it off.”

And at the Loft, it didn’t matter if you had a dance partner or not. It was all about “individual free-form dancing,” says Lawrence. “This was the breakup of partner dancing. You didn’t have to be interested in a guy or a woman or whatever . . . The driving element was the music and the dancing. And the sex was something that you might think about later.”

Eventually, the Loft would move around to other, nonresidential locations, such as Union Square Ballroom and the Ukrainian National Home social hall. And four years after Mancuso’s death, his spirit lives on in Loft parties everywhere from London to Japan.

And the Loft forever changed the way DJs such as Benitez see the dance floor. “It just became a connection to my soul, to myself, and an awareness of being present and in the moment. I was living in that moment,” he says. “It had all these souls in the same place dancing together and alone at the same time, living in their moment. You felt like you were part of the family.”