Yes, the dominoes of marriage equality in individual states have tumbled with a surprising velocity. My first Op-Ed column, in June 2011, noted that New York had just become the sixth state in the country to legalize same-sex marriage. The count today is 37 states and Washington, D.C. I’m amazed at this still.

And I marvel that just over two years ago, Hillary Clinton hadn’t yet spoken up for marriage equality, which is now such a given among Democrats that they characterize Republicans’ resistance to it as damnably backward and baldly uncivilized. That’s an enormous change.

But it’s not so dizzying or difficult to comprehend when you think about the simple logic behind same-sex marriage: You can’t relegate the commitments and loves of an entire group of Americans to a different category, marked by a little pink asterisk, without saying that we ourselves don’t measure up. You can’t tell us that you consider us equal and then put perhaps the central, most important relationship in our lives in an unequal box. It’s a non sequitur and a nonstarter.

A Supreme Court judgment for marriage equality wouldn’t be a rash swerve into uncharted terrain. It would merely be a continuation of the journey of gay Americans — of all Americans — across familiar land, in the direction of justice. It would be a stride toward the top of the hill.

And the first steps go back much further than 2011, than DOMA, than AIDS, even than the Stonewall riots of 1969.

Next month, in fact, is the 50th anniversary of the first “annual reminder,” a picket in Philadelphia for gay civil rights. It commenced on July 4, 1965, with just a few dozen gays and lesbians, and occurred yearly through July 4, 1969, as “Gay Pioneers,” a short 2004 documentary, eloquently chronicles.

Three newer documentaries also underscore the sweat and tears that preceded the present moment. PBS just posted on its website “Limited Partnership,” the story of a committed gay couple’s efforts, starting in the 1970s, to prevent United States immigration officials from deporting one of them. On Monday, Yahoo Screen will introduce “Uniquely Nasty: The U.S. Government’s War on Gays,” which rewinds to the 1950s.