Martin Luther King spoke about the promise of the American dream, unity, peace and the inalienable rights of man, which in itself is enough to cause an echo down the years.
He was speaking to one of the biggest crowds of people ever to march in Washington, around 250,000 blacks and whites calmly asking for equal employment rights, and that's enough to make history too.
But what really gave his words rocket fuel - aside from his use of rhetoric, emphasis and cadence, skilfully building the emotions of anyone who hears it to a crescendo - is that it was reported in newspapers, on television and radio, and went around the world.
The 'I Have A Dream' speech was given the same kind of blanket coverage as John F. Kennedy's presidential inauguration. King spoke for just 17 minutes, but his words are still being heard.
Nearly half a century on, America has a black man in charge. Black women can ride the bus, the law does not discriminate by skin colour, and the children of slave-owners - Lord Sebastian Coe, for example - can sit down with the children of slaves - like Usain Bolt, who grew up in the same place Coe's forebears ran plantations.
But King said in 1963 "the Negro is still not free" and there are plenty who'd say not much has changed. In America, Britain, and the world at large poor people are more likely to be black than white. We're more of a global community these days but there are whole nations - predominantly with darker skins - who live "on a lonely island of poverty in the midst of a vast ocean of material prosperity".
The richest country on earth is America. The poorest place within it is Allen, South Dakota, where the population is 96.4% native American. Thirty nine million people live in poverty - the same proportion of the population as Indonesia. Three quarters of impoverished households are headed by women. Ten per cent of whites are poor, compared to 27 per cent of blacks.
King said people of colour had been given a "bad cheque... marked 'insufficient funds'" by those in charge of the money. Today most of the developed world is cutting back on anti-poverty measures, including the USA. It has 50 million people without healthcare, and thousands queue through the night for a handful of free clinics.
America also has the highest infant mortality rate of any industrialised nation, and it must surprise anyone that the world's richest country allows babies to die when it has the money to save them - or at least, has more money than Greece where infant mortality is better.
There is no sense of national or international brotherhood like King imagined, and the introduction of human rights for all has not produced global peace, justice or freedom. But at least there are now laws that say you cannot judge someone by their skin, and generations have since been born for whom such an idea makes so little sense such laws seem ridiculous.
The fact is that the "jangling discords" of humanity are never going to become a harmonious brotherhood, because while we can strive for greater freedoms we're never going to be able to not discriminate.
We all do it. We judge people by their manners, the effort they make with their hair, the job they do. We make assumptions about people we meet and even those we haven't based upon their education, where they're from, their age, name, height, and weight. It's part of the human condition and it's the reason why, in newspaper stories, you will always see a reference to the subject's age, location and an indication of their wealth.
We like to categorise people, which is why we absorb without noticing reports which say the missing girl came from a terraced house with a well-kept front garden, or the celebrity has a 10-bedroom mansion with an open-air jacuzzi, or the murderer drove a Vauxhall. All those little facts help us to make our minds up about other people, which is why it makes a difference to say 'the stripper, aged 17' rather than not mention her age at all.
If you stop to think you'll find you discriminate dozens of times a day. There'll be someone in front of you in the street you smile at because they're attractive, or they're walking with a puppy so they must be nice. There'll be someone you choose not to make eye contact with, on the basis of the clothes they wear. You'll discriminate over which sandwich to have at lunch because you've always thought egg mayonnaise was either for chavs or a special treat, and you'll patronise one coffee shop over another because you prefer their brand, decor or cost.
It's a case of one word being used in two opposite ways, because to be discriminating is seen as a good thing meaning you're choosy or analytical, whereas to discriminate is a bad thing showing you're ignorant and stupid.
But then Martin Luther King, contrary to reports, did not call for an end to discrimination. He asked for skin colour not to matter, and that means black and white alike may be categorised and sorted by us in that normal, human, and mostly harmless way we have.
And he also said: "Whatever affects one directly affects all indirectly. For some strange reason, I can never be what I ought to be until you are what you ought to be. You can never be what you ought to be until I am what I ought to be. This is the interrelated structure of reality."
Everyone is in theory subject to being poked fun at, to be praised or criticised, to be subject to ridicule, to worship as they please, to spend their lives in the pursuit of their own personal happiness. In practice, some types of people find those things easier, and there are others - purely on the basis of their colour, faith, weight, or other factors - who are off-limits.
There are some jokes which can't be told, some views which cannot be expressed. They are considered offensive to the majority and so go unspoken even though the best way of changing an offensive point of view is to expose it to as many people as possible. Anders Behring Breivik is allowed to write letters expressing his hateful views to the fans of his Norwegian killing spree, which many think promotes his cause. It might do, but it's also the best way of showing how ridiculous it is.
King called, above all things, for the freedom to be yourself. Whether it's good or bad you'll find out when other people react to it, but there was a time when talking about equal rights for black and white was as offensive to the majority as the opposite view would be now.
What is offensive changes over time, but things get better only if we have the freedom to discriminate for ourselves. To choose our own jobs, our own politics, our own loves, whether we are black, white, fat, thin, rich or not so rich, without someone telling us we can't.
Not being allowed to do something is not the same as being incapable of it.
It might be a dream, but it's good enough for me.