When Harry Potter discovers the enchanted Mirror of Erised he becomes transfixed with watching his dream come 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 manage to snap out of the mirror’s grip. But as he’s about to find out, its hypnotic powers are not the only danger. By exposing your hearts true desire, what the mirror reveals can also be turned against you by the 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 a lot on the philosophies underlying that noble art of self defence, where it’s not the strongest fighter who wins, but the one who manages to offset the opponent’s centre of gravity. If you achieve that, you gain superpowers.

Chris gives us the interesting example of how fledgeling diapers company Drypers managed to gain market share by using their opponents power 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. The way it works is you buy a bag of P&G diapers containing coupons, which you send in to 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.

Usually the problem with catchy anecdotes is that they tend to be generalised into “business laws” that doesn’t really help you navigate your particular 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. In either case I do know I need to put his latest book on my reading list.