There's three types of thinking: vertiginous, vertical and lateral.

Vertiginous is an old favourite; there I am dizzied by the height, dazzled by an idea, which is usually insubstantial and so unable to support either it's own weight or any worthy scrutiny, nevertheless there's an obligation in me to check it out. Chasing chimeras, I simply have to. Thus I step off the precipice and find there's absolutely nothing to cling on to, the idea or whatever notion it is I'm chasing is as concrete as snowflake, and I land with thump. Take the Shepherds Bush plague pit I wrote about a few days ago - what an illusion that turned out to be.

So that's vertiginous, what about vertical, what's that? Well, that's straight up, linear thinking. Problem oriented, heavy on the reality of an issue, but featherweight on daydreams (that's the province of vertiginous). Vertical thinking is a foundation layer of business: there's a problem, this is the solution, and it will be pushed through at all costs. It may not fit, or even fix the thing at hand, but it's what has been decided upon and that's all that matters. Debatable whether this works, my experience is mixed here, sixty forty against.

My preferred thinking mode is lateral. The brainstorm. Get a clean sheet of paper, tell everyone to disengage their vertical thinking, ignore those boundaries, let loose whatever ideas pop up, and watch that pristine sheet fill up. This is idea generation at it's finest. Everything is a candidate, even the most peripheral and far-fetched can help.

I'm pretty good at lateral thinking. Partly because I've read a lot about it, partly because I love it's contempt for prescription (there's no: "don't do", it's all; "this might well work". I can't get enough of that openness); then partly because I need to be. Circumstances, the unexpected happening, they're why. Something utterly unexpected occurs and it needs fixing. Let me give you an example from Archimedes's life. I had an hour or so in a coffee shop with a friend on Saturday. We left and marched straight in to dust-storm roiling through Shepherds Bush. Clouds of builders sand and tree pollen. I swallowed most of it and what I did n't went in my eyes - I wear spectacles by the way so that's quite an achievement. Anyone enjoy the sensation of something stuck in your eye ? Painful twinges every time you blink ? Did n't think so. Seeing should be visual not tactile.

I doused my eyes with water to try and flush out the parts of Shepherds Bush that were stuck in them. Nothing. Sneezing and blowing my nose as I'd done on numerous other occasions. Nothing.

So what I did next was leverage Mother Nature's bounty; I bought an onion. A basketball sized onion. If there's one thing that can make me weep, it's one of these. I chopped this monster up as finely as I could, imploring the fumes to do their worst. They did. I wept me a river. Eyes in full flood can dislodge anything. To exaggerate the effect peeling onion can stimulate, I hovered millimetres above it, so both eyes were smarting and stinging; it's how I imagine driving through a cloudburst must be, I could barely see anything, in fact I'm surprised I've any fingers left, but it broke the log-jam. It did the trick. I can see again

Thank you Edward De Bono for the lateral thinking concept; thank you Nature for onions.