We assume everything is always the result of logical, straight-line thinking.
But that isn’t always true.
For instance, take the rear-view mirror in your car.
The rear-view mirror was invented more than 100 years ago by racing car driver Ray Harroun.
He was more of an engineer than a driver.
But he wanted to enter the first ever Indianapolis 500 race in 1911, so he designed a racing car called the Marmon Wasp.
His first innovation was that his car was a single-seater.
In those days, every car had two seats – one for the driver, one for the mechanic.
The mechanic was there to fix the car if it broke down, and he would also tell the driver where the other cars were.
Harroun knew his car wasn’t going to break down so he didn’t need a mechanic.
But on the day of the race, the other drivers complained.
Without a mechanic, he would have no-one to tell him where the other cars were – it could be a real danger to the other drivers.
That’s when Harroun showed them his second innovation.
He didn’t need a mechanic to tell him because he made a large mirror with four metal legs – he fitted it above the steering wheel.
That way, without taking his eyes off the road, he’d always know who was behind him.
No-one had heard such an idea before but they couldn’t argue – it made sense.
So Harroun started the race at number 28 out of 40.
Over the six hours and 42 minutes of the race, he averaged 74.5 miles per hour.
A fast speed for 1911, but not as fast as some of the other drivers.
They would roar past, but they wore their tyres out and had to change them.
In 1911, tyre-changing wasn’t the speedy process it is in modern Formula One.
It was slow and cumbersome, which is where his opponents all lost time.
Harroun only had to have four tyre changes.
His nearest opponent, Ralph Mumford, had to have 14 tyre changes.
Harroun won the first Indy 500 by more than half-a-mile.
And he did it alone, without a mechanic looking around to help him.
The papers called his new device "seeing without turning" (the name rear-view mirror hadn’t been invented yet).
Soon everybody wanted one, and today no car is made without one.
But it was only much later the truth came out.
After he retired, Harroun explained the Indianapolis Speedway had been paved in 1910.
They’d used 3.2 million bricks and it was bumpy as hell.
As Harroun said: "It shook so bad I couldn’t see a damn thing in the mirror anyway. But I made sure no-one knew that but me."
He kept it quiet because he didn’t want to be disqualified.
The real purpose of the mirror wasn’t to see what was happening behind anyway.
The real purpose was to let him race without a mechanic.
That meant his car was lighter than the others, and the tyres wouldn’t wear out so fast.
That’s all the mirror ever was, an excuse to get rid of the extra weight of a mechanic.
So the thing we all take for granted as a safety feature was never invented for that.
It was invented to get round the rules.
And today, every racing car is a single-seater, and every road car has a rear-view mirror.
Because creativity doesn’t always work in straight lines.
It’s good to remember that, because briefs aren’t supposed to be straitjackets.
A brief should be the floor, not the ceiling.
As John Webster always used to say to me: "You have to leave room for accidents."
Dave Trott is the author of Creative Mischief, Predatory Thinking and One Plus One Equals Three