Every child will, at some point, ask their parent where money comes from. And every parent will think it comes from hard graft and there used to be a lot more of it until it got used up on nappies, massive supermarket shops and family holidays.
But this week, I found the actual, real answer to that question. I went to the place where money does come from.
I can't actually tell you where I went. In order to get into the place, I had to agree not to disclose the location, which all felt a bit cloak-and-dagger when I read it on an email.
Then I walked in, and understood why.
I can tell you it was a rather unprepossessing factory. And I can also tell you I went through some pretty onerous security to gain access, including having to hand in my passport, surrender my wallet and change my shoes.
Then I walked through an airlock, with a security guard trailing along behind me, turned a corner, and saw the people who have a licence to print money.
It’s a company called De La Rue, and it prints banknotes for countries all over the world, including our own. It has been going for the best part of 200 years, creating currencies for dozens and dozens of nations, and doing so in huge numbers. For this company, with its rather anonymous factory and smiling early-morning workers, is the world’s biggest maker of banknotes.
The challenge is it has to produce them in vast quantities, but also make them almost impossible to forge.
"It has to be almost impossible for someone to make a single copy, but straightforward for us to make millions," as one of the managers said to me. And as if to prove a point, there in front of me was a fortune.
On the day I visited, it was Kuwaiti dinars rolling off the printing press. It is an exhaustive process, involving applying ink and various security devices, drying, pressing, finishing, varnishing, cutting, checking and goodness only knows what else.
But here, sitting in a huge pile, were notes nearly at the end of the manufacturing process. On each sheet, there were nine columns and five rows of notes. That's 45 banknotes on each sheet.
And there were probably 2,000 sheets in the pile. Possibly more. This unassuming pile, covered by a piece of cardboard, was worth around £2 million. Such is life inside a money factory.
Little wonder, then, you can’t bring in a bag, or your wallet, or that security is tight. They count every sheet, check every note, and account for everything that has gone in and come out of the factory. Rarely have a I gone to a place that felt so efficient.
It isn’t noisy, like an old-fashioned factory. There’s no clanging or shouting, dust or oil. It’s clean and controlled and impressive, with machines the size of a small bungalow slowly churning out money in its various stages but in vast quantities. Every week, De La Rue produces so many banknotes that if you stacked them on top of each other, they’d go to the top of Everest - twice.
It’s astonishing the world has EVER needed that many notes - but every week?
It turns out notes often need replacing. They wear out after just a couple of years or they might get inadvertently destroyed (is there a more annoying mistake in the world than washing a tenner in the pocket of your jeans?), or they might need updating.
Notes get phased out and replaced by higher denominations - the £1 note, for instance, is a thing of the past and one day, I guess, the £5 will go the same way.
But what fascinates me is money relies on all of us trusting in it. The process of creating it is, genuinely, impressive.
A banknote contains so many subtleties I’d never thought of, to do with texture and feel and care. It’s also got three layers of security - the ones we can all see, the ones you can see under special circumstance (ultraviolet light) and the so-called "covert" ones hardly anyone knows about.
But it is still, at heart, just a piece of lovely paper. A tenner is only worth £10 because you and I agree it is.
The days when you could swap a banknote for gold have long since gone.
The system relies on us - you, me, everyone - believing in what is basically quite a weird concept - that this bit of paper is worth something special. It works as long as trust that the value of these notes isn’t about to plummet, in which case the whole shooting match falls apart.
Little wonder we, along with the rest of the world, want our banknotes to look impressive.
So next time you’re whipping out your purse, have a look at that banknote. Look at the care and effort that’s gone into it, at the engraved picture, the various holograms and security strips that make it what it is. It’s made in Britain, just like so many other notes swirling round the world. I think we can be rather proud of that.
Sometimes in life it really is the little things that make you smile.
The acts of kindness, the in-jokes, the understated jokes. Or, for that matter, the slip road from the M1 link road.
You all know the place I’m talking about. You’ve come off the M1 and you're heading into the middle of Watford.
You put your foot down along Stephenson Way (anybody know which Stephenson that was, by the way - always wanted to know...answers to @adamparsons1 please) and you’re heading towards town.
Then you see the roundabout looming ahead and you don’t want to turn right.
You want to go straight on so, in a normal world, you would slow down, manoeuvre over the roundabout and go on with your day. But here, of course, is where things change.
Because us locals know there’s that slip road off to the left that lets you avoid the roundabout completely.
It’s barely signposted and not the sort of turning you would take if you were from out of town. It is, in short, a bonus for living on the patch, a sort of thank you from the town of Watford.