Donald MacInnes: How I came over all funny when I was confronted with money

Do you regard money as being real? Does it matter to you if you can't hold it in your hand? Would you rather have your savings inside a mattress, or do you just like to know how much you have, with someone else looking after it? Someone in a suit, perhaps? Like a banker? (Stop screaming at the back. There's almost nothing to be scared of).

Since time immemorial (which, according to Cave-apedia, refers to the period just after the wheel was invented, but just before anyone figured out what to do with it), cash has had a symbiotic relationship with society. Ever since Oswald the Sceptical bought a handful of mud from Edwin the Nervous for one of those nice shiny black pebbles, we have been delightedly swapping hard currency for goods. (And services, if you want the mud applied by hand).

And while the technological revolution would seem to be convincing us that cameras, telephones, video game consoles and televisions can safely exist within a box the size of a Ryvita, perhaps the biggest impact of all of this future-tech is that we finally do away with currency. Or start aiming for a smartphone the size of a Ritz cracker.

The other day, my wife and I were at the Tesco checkout. The lady swiped the last of our groceries and announced the total: just over £40. Given that my wife and I have yet to set up a joint account for things like food shopping, we usually split the bill on our debit cards. However, instead of inserting her card into the little machine, my wife did something which quite took me aback. She handed me a £20 note. For those of you under the age of 25, I should explain that a "£20 note" is a piece of paper that you can exchange for iTunes credits and KFC. How many Rihanna tunes you download and how many buckets of chicken you consume will determine how many "pounds" you get in return for your "£20 note".

Now, I may be an old, old man who once bought a Clash single in Woolworths, but even a Luddite such as I can see the benefit of not having to lug around handfuls of paper money and enough jangling change to use as ballast on a nuclear submarine. (By the way, if you don't know what the words "a Clash single in Woolworths" mean, please put this paper down or switch off your digital platform and go and watch TOWIE).

So there I stood in Tesco, gazing at my £20 note like it was an old friend. I was suddenly seized by the desire to spend it. And I could tell, by the way The Queen was looking at me from her picture on the note, that she wanted to be exchanged for something. So I swapped her for a couple of scratch cards, leaving £16. If I spend it between now and next week, I'll of course let you know.

Twitter.com/DonaldAMacInnes