We all like to believe that history is progress; that things get better, that we learn as we go on. Well, this World AIDS Day, we can see that it isn't always so.
25 years on from those huge tombstone ads saying "Don't Die Of Ignorance", some people are still dying in the UK because they don't get tested for HIV till it's too late. And people are still getting HIV through ignorance of their personal risk.
Treatment for HIV can keep you alive to old age, enable you to work and have a family. So why are people still so reluctant to test that one in four people with HIV in the UK are undiagnosed, and half of those who do get tested do so only after they should already have started treatment?
One major reason why we're still seeing more than 6,000 new HIV cases each year is that people are far more likely to pass the virus on if they're not diagnosed and on treatment. And they're not using condoms because they simply don't think it's going to happen to them. Sometimes, it already has.
Next year, there will be more than 100,000 people living with HIV here in the UK; more than ever before, though a quarter of them don't know it yet.
In the '80s, when the total was far smaller, we were screaming from the rooftops about safer sex. At one point, it seemed you couldn't turn the telly on after 9pm without coming across something about safer sex, or a blushing presenter wrestling with a condom demonstration.
So in 2011, according to the media, what did we worry about with HIV? Getting it from fish pedicures. Whether police officers needed emergency treatment for someone spitting at them. Whether the power of prayer can substitute for medical treatment. Whether a swimming pool needs disinfecting because people with HIV had been in it. None of these are real risks - unprotected sex is.
I wonder how many people who abandoned fish pedicures this year always use condoms with new sexual partners? An increasing number of people, young ones in particular, don't. The fact is, many people know less now about HIV than they did after those campaigns 25 years ago. It's not just my observation - an Ipsos Mori poll undertaken for the National Aids Trust shows steadily declining levels of knowledge over the last decade, with one in five people now unaware that condoms protect against HIV - more than double the number a decade ago.
As Lord Fowler, who presided over that campaign against ignorance in the 80s, says, you wouldn't advertise a product once and then wonder why sales had dropped off decades later.
We aren't telling enough people, often enough and in enough different ways, about the risks they are taking with their sexual health. At Terrence Higgins Trust we constantly try to devise new ways of getting the message across, often in collaboration with other sexual health charities, but we're often drowned out by other media messages saying that everyone's having sex, it's easy and don't worry about any consequences.
When we do get an information campaign out, there are people who don't think we should be talking about things like that, or at least not in terms the public understand. Our new campaign for World AIDS Day, showing young men with condoms in their pockets, was delayed because it was "too near the mark" for the printers.
The slogan? "Smart Arse/Clever Dick" - hardly pornographic by today's standards and yes, the young men were wearing their clothes. As a society we're still, after all this time, too often unwilling to face reality and do what's needed.
So this World AIDS Day, Terrence Higgins Trust is promoting three simple things for people to do.
One, have a sexual health check up if you've ever taken a risk (and if you keep taking risks, make that a regular check). Two, use condoms with new partners until and unless you've both had a check up and agreed on monogamy. And three, if you do have HIV, find out more at www.myhiv.org.uk about how to manage your health and treatments.
It's not rocket science.
It will keep you and your loved ones well and safe. But not enough people are doing it, so I guess there's one more thing I'd like to ask you to do this day; tell someone else about HIV, show them this article, put something on a bulletin board or anything else that might do one little thing to put a chink in the great wall of ignorance that still, sometimes fatally, surrounds HIV.