When Harry Potter discovers the enchanted Mirror of Erised, he becomes transfixed by the vision of his deepest dream coming true. Just beyond his reach, he sees his loving parents brought back to life. Cautioned by Albus Dumbledore — “many a man has wasted away before it” — Harry eventually manages to snap out of the mirror’s grip. But as he soon discovers, its hypnotic power is not the only danger. By exposing your heart’s true desire, the mirror’s revelations can be weaponised by an enemy.

I thought about that the other  day when I listened to Chris Lukassen He just published The Product Samurai : a product manager’s guide to continous innovation. He’s also a judo champion and he draws heavily on the philosophy of judo, where victory goes not to the strongest fighter, but to the one who offsets their opponent’s centre of gravity. If you achieve that, you gain superpowers.

Chris shares an intriguing example of how the fledgling diaper company Drypers gained market share by turning their opponent’s strength to their advantage.

Drypers should have been killed instantly by Procter & Gamble, which dominated the market thanks to a finely tuned system of discount coupons. These are less common in Europe, but important drivers of consumption in the US. You buy a bag of P&G diapers, send in the coupons inside, and receive a discount on your next purchase. Simple mechanics, but it takes a lot of marketing infrastructure to create a nation-wide programme and once you have one in place it’s usually a powerful barrier to entry, effectively keeping newcomers at bay.

So what does Drypers do? They simply announce that “from now on we too will accept P&G discount coupons”.

So simple, and of course, a true judo-move. The people at P&G must have felt there should be a law against it.

The problem with catchy anecdotes is that they often get generalised into ‘business laws’ that don’t help you navigate your specific terrain. That’s why I really liked what Chis did. Instead of giving us yet another high concept formula, he shared a very actionable tactic.

He says this: If your opponent is a listed company and you’re trying to figure out in what direction that company is pushing, simply flip to the chapter Acquisitions in their annual report.

And that’s what gets me started with thinking about the mirror of Erised. Because it’s true if you think about it: An acquisition strategy is hard to hide and it clearly shows your ambitions. That can be turned into a vulnerability, just as Voldemort based his attack strategy on what he knew about Harry Potter’s inner wishes.

The idea that your opponent’s acquisition strategy gives a clue to their relative weakness seems counter-intuitive, but it also feels just about right. I’m still not sure whether that’s because it has a kernel of truth, or if I was just taken in by Chris’ natural authority. Either way, I know I’ll be adding his latest book to my reading list.