I started off a recent day by reading the obituary of Wesley A. Brown. I did not know him and, in fact, had never heard of him. He was the first African American to graduate from the United States Naval Academy. He was the sixth black man admitted and the only one to successfully endure the racist hazing that had forced the others to quit. He graduated in 1949. I was 8 years old at the time and had no idea of the sort of country I was living in.

I did not know that schools in some parts of the country, but especially in the South, were segregated. I did not know that blacks and whites could not marry. I did not know that the balconies in movie theaters were reserved for blacks only — as were seats in the back of the bus. I did not know about black and white state parks, water fountains, motels, hotels, funeral homes, churches, bar associations, cab associations, medical associations, cab stands, lunch counters and so much more, including a whole system of justice.

But I learned and I am still learning — the Brown obit was a little lesson in itself — and I simply cannot get over what a mean, racist nation we were. Blacks by and large were treated worse than most minorities, but Americans could be awful to just about anyone. In David M. Oshinsky’s book about polio epidemics (“Polio: An American Story”), I came across Yale Medical School’s policy regarding minority admission in the 1930s: “Never admit more than five Jews, take only two Italian Catholics, and take no blacks at all.” This was Yale. Boola-boola.

What I did not know, I fear others do not now know. If they are ignorant of the past, therefore they are ignorant of the present as well. They do not know what a miracle has been pulled off — how a nation that once contained so much bigotry now contains so little. I am not a fool on these matters, I think, and I recognize in the disparity of support for President Obama — working-class whites don’t like him much — the residue of bigotry, but still the big picture is that Obama is a black man and he is the president of the United States. Mamma, can you believe it?

We live in a land of rapid cultural shifts. After Obama announced his support of gay marriage, 53 percent of Americans said they were with him. Just six years earlier, only 36 percent of Americans said they supported gay marriage. This has been a cultural upheaval, no doubt abetted by television (“Will & Grace,” “Modern Family,” “Smash”) but also by a general liberalization of society — more of everything except marriages. Soon, only gays will marry.

It’s hard to know how deep these cultural changes go. The question has real relevance when it comes to the Middle East. Do revolutions powered by Facebook and Twitter mean that minds, as well as political structures, have been reordered? Does the wearing of Western clothes mean the adoption of Western cultural norms? Maybe a bit. Maybe not at all. We shall see.

The same holds for America. How deep are our own cultural changes? Some insist that not much has changed. They cite a persistent American racism. There are many such examples — not all that many, actually — but they are newsworthy because they are exceptions to the rule, not what we expect. Once, though, we expected that a black man would be harassed into quitting the Naval Academy on account of race — that this racism was ordinary, normal and in no way a violation of the rules of the place. (Jimmy Carter, a midshipman at the time, was one of the few to offer support to Brown.)

We have a way to go. Gays still can have a dicey time of it, blacks, too — and women too often are the victims of violence. But when I read the obituary on Wesley A. Brown, I was shocked once again at the depth and meanness of our racism and then just plain dumbstruck by how far we have come. The new field house at the Naval Academy is named for Brown. He called it “the most beautiful building I’ve ever seen,” but he was wrong. It’s not a building. It’s a monument.

cohenr@washpost.com