Mainstream American culture had little room for homosexuality in 1979, when Robert Mapplethorpe photographed Brian Ridley and Lyle Heeter in their full sadomasochistic regalia. At work, gay employees were largely closeted. In many states, expressing their love could be criminal.

Mapplethorpe spent 10 years during this era documenting the underground gay S&M scene—a world even more deeply shielded from public view.

His intimate, highly stylized portraits threw it into open relief, perhaps none more so than Brian Ridley and Lyle Heeter. Both men are clad in leather, with the submissive one bound by chains and the dominant partner holding his reins in one hand and a riding crop in the other.

Yet the men are posed in an otherwise unremarkable living room, a juxtaposition that adds a layer of normality to a relationship far outside the bounds of what most Americans then considered acceptable. The picture and the series it was part of blew open the doors for a range of photographers and artists to frankly examine gay life and sexuality.

Nearly a decade later, Mapplethorpe’s work continued to provoke. An exhibit featuring his pictures of gay S&M scenes led to a Cincinnati art museum and its director’s getting charged with obscenity. (Mapplethorpe died of AIDS in 1989, one year before the trial began.)

The museum and its director were eventually acquitted, bolstering Mapplethorpe’s legacy as a bold pioneer whose work deserved public display.