"You're going to tell me you're witches, aren't you?"
"Yes," said the leader of this little coven, "and what you said about magic was very offensive."
I had chosen witchcraft as an example of supernatural tosh, to remind the audience about how the rise of science had improved everyone's lives.
To get the point across, I had tried to avoid giving offence to those of a "religious persuasion" who would be on the look-out for any criticism or "slight".
My self-censorship was to no avail as even witches have adopted the PC term "offensive" these days. I thought I was safe talking about all sorts of nonsense such as casting spells and charms, crystal healing, reiki, spiritual guides, homeopathy, reflexology, aromatherapy, and contrasting this with the real benefits of scientific medicine. Which, according to my short list, are increased longevity and health, the use of anaesthetics and antibiotics, cardiac treatment, safe surgery and organ replacement. The list is long.
But we casually forget even the obvious benefits of science. We forget, for example, that until the 20th century most of human misery was toothache, from early childhood to late adulthood, at which time teeth painfully decayed. Witchcraft did not do away with toothache, science did.
Apologising to witches was a step I could not take and, despite their youthful charms, I would not treat hocus pocus with "respect". I did not apologise.
But the teenage witches made me wonder if you could get a qualification as a witch. It turns out there are dozens of colleges and groups and hundreds of witches offering training. Distance learning is widely available.
It is a rich market for FE colleges and one at least is already offering a two-stage course. Amazingly, student destinations are listed. They include one student who became a druid, two who became wiccans and another who started an ecological society.
There also seem to be an alarming number of tutors in FE and adult education involved in this weirdness, and student pagan societies are on the increase.
Reading the biographies of teachers of witchcraft and the like, they seem to follow a pattern. They start with an interest in the environment and ecology, which becomes a spiritual search that finally leads to paganism.
What all this superstitious nonsense has in common is that it puts nature first. Humans are put in their place as part of the natural scenery.
It is a veiled form of human self-hatred that puts rocks and trees before people. That is if we take its implication seriously and stop thinking of it as harmless fun. As Hallowe'en approaches, it is worth reminding ourselves that it was once just a bit of simple fun, a single day when old superstitions and silliness could be revived to entertain children. Now, everyday seems to be Hallowe'en.
Television is full of programmes about witches, ghosts, ghost whisperers, angels and demons. The sick thing is that they are presented as quite normal phenomena. Gone are the days of stylised camp horror movies.
Superstition is the new soap. It is time for an intellectual witchhunt. We need to remind ourselves of our humanity and what makes us human rather than go on infantile day trips into primitivism and superstition.
What makes us human first and foremost is science. Science is what Bacon called the intellectual challenge to seek "knowledge of causes, and the secret motions of things; and the enlarging of the bounds of human empire, to the effecting of all things possible". In the 17th century, humanity could aspire to the effecting of all things possible. But in the 21st century we seem to lack all confidence in the future and are more comfortable with sentimental primitivism.
Although we do not have the confidence to celebrate scientific achievements unimaginable to Bacon, there are occasional attempts to defend science.
Initiatives such as Prospect's new Charter for Public Science. But charters are not enough to tackle the collective amnesia about science and its benefits.
Colleges and schools could make a start in restoring confidence in science, but they just seem to be part of the problem. Science is expensive to deliver and students find it "boring", which means challenging and difficult.
There are more courses on offer in the FE sector on reflexology and aromatherapy than chemistry. Even the new science curriculum for schools seems to reflect the anti-science culture.
Pupils will find themselves discussing the relative merits of witchcraft and science as different world views, rather than learning the periodic table.
The great thing about bobbing for apples is that it leads curious young intellects to the scientific discussion of density. Boring? No apologies for that, either. We should always, and at every opportunity, celebrate science.
Dennis Hayes is head of the centre for professional learning development at Canterbury Christchurch university