For most of human history, homosexuality has been condemned on three grounds: that it is a sin, a crime, and a sickness. Despite the emergence in recent decades of gay-affirming scriptural exegeses, many major religious denominations continue to regard homosexual acts, if not the homosexual inclination itself, as immoral. As to the second rationalization, only in 2003, with the Supreme Court case Lawrence v. Texas, was gay sex decriminalized across the United States, thereby lifting the menace of legal sanction that had long shadowed gay lives. And thirty years earlier, a similar liberation had taken place when the stigma of mental illness was officially disassociated from same-sex attraction.

For this latter advance in human understanding, we largely have Frank Kameny to thank. A Harvard-trained astronomer fired from his job in the Army Map Service in 1957 because of his sexual orientation, Kameny was the first person to challenge the federal government over its anti-gay discrimination policies. Understanding that the rationale for barring highly qualified homosexuals like him from public service rested not only upon the McCarthyite claim that they were liable to subversion, but also that they were mentally unfit, he took it upon himself to change the scientific consensus. Kameny’s most consequential insight as an activist was that it was not the homosexual who is sick, but rather the society that deems him so.

“The problems of the homosexual stem from discrimination by the heterosexual majority and are much more likely to be employment problems than emotional problems,” Kameny wrote in a 1969 letter to Playboy, responding to an article that advised “therapeutic methods” for treating the male homosexual. (One suggested method entailed reading said magazine not for the articles but the pictures.) Doctors “would be of greater service to the harassed homosexual minority,” Kameny concluded, “if they ceased to reinforce the negative value judgments of society and, instead, adopted a positive approach in which therapy for a homosexual would consist of instilling in him a sense of confident self-acceptance so he could say with pride, ‘Gay is good.’”