A car number plate, a luxury yacht, a gym sweatshirt, a copy of The Beano and a chesspiece. What do they all have in common? They are all items that have made the news over the past week or so either because they have sold at auction or are soon to be sold.

This snapshot of the variety of sought-after lots that can appear at any one time is one of the best illustrations I know of why this is a great business to be in, whether as an auctioneer, specialist, dealer or private collector.

Take the yacht, for instance. The 85ft motor yacht, named Caviar, had once belonged to a criminal and had been auctioned off by the police after being left abandoned for some time in Southampton. Although valued at several millions pounds, a young family snapped it up for just £66,000. Ok, they then spent a further £300,000 doing it up, but this auction opportunity gives them the chance to live the dream in considerable style as they set off on a round-the-world trip.

Renamed Juliette after the couple’s young daughter, the yacht will eventually return to these shores, providing the family with a substantial uplift o their original investment.

What is art? It’s a question whose answer has evaded us for centuries. Attempts to define it clearly have never worked because, like the wind, we can see and feel it all around us, but can never quite pin it down.

Frustrating as this might be, mostly we know art when we see it; this elusive quality is what makes it so fascinating and versatile. In turn, that means that art is forever reinventing itself and can appear in the most surprising forms, especially these days when fairly mundane items created for a different purpose are remodelled or redefined as art – folk art, for instance.

A good example of this is the EU entry gate sold at auction last year when the entire contents of Terminal One at Heathrow came up for sale. The hammer came down at £1000 and no one thought any more about it until the Royal Academy Summer Show opened a couple of weeks ago and there it was, transformed by Banksy into a new work of art combining humour and political statement. The gate itself looked almost the same as it had done when auctioned off. Banksy had added a shutter and painted the words Keep Out on it, rendered as Keep Ou because his signature rat had removed the T to use it as a hammer to break the padlock at the bottom. Not to everyone’s tastes, maybe, but with Banksy’s transformative touch, this work of art will be worth a great deal more now than its original auction price.

In many ways, what must be one of the most astonishing auctions of recent years has just taken place. The lot in question? The gun with which Vincent Van Gogh is supposed to have killed himself.

The astonishing thing about it is that even the auctioneer selling it was clear that no evidence exists to show that this was the actual gun, yet it made the equivalent of £144,000.

The troubled artist died a few days after walking into a field near Auvers-sur-Oise and shooting himself in the chest. It was July 27, 1890. No one knows what happened to the gun, but in 1965 a corroded revolver was dig up in a field near the chateau where he had been staying and tests indicated that it had been in the ground for between 50 and 80 years – so about right.

That’s as far as it goes, so the buyer was acting in faith, just as pilgrims making their way to shrines that house anything from St Catherine’s finger to a thorn from Christ’s Crown of Thorns are also taking it on trust that these relics are genuine.

Ordinary everyday items acquire a unique symbolic status when they have been touched by inspirational figures like Van Gogh, who will remain forever out of reach themselves. Akin to holy relics, they hold a special attraction for bidders at auction.

It’s that time of year when sporting heroes come to the fore again. Lewis Hamilton continues his dominance of Formula One, Rafa Nadal wins his 12th French Open title – aged just 33!! – and England’s Women’s Football team leads its groups in the initial stages of the World Cup… I could go on.

Along with music, sport serves a vital role of bringing all sorts of disparate people together in a common cause – something we need now more than ever – and it is not always the obvious candidates who become heroes. Look at how the Mexican underdog Andy Ruiz Junior, trolled for appearing overweight and flabby, took out Anthony Joshua in the boxing ring at the beginning of the month.

Sport is not just about achievement and titles; above all, it is about character. That’s why Babe Ruth’s baseball jersey sold for $5.6 million at auction on June 15, to become the most expensive piece of sports memorabilia in history, breaking the previous record, which was also for a Ruth jersey.

Known to have survived largely on hot dogs and beer, Ruth was a big man but, along with his penchant for cigars, he could not have been in the best shape and, indeed, he died of cancer aged 53. This didn’t stop him from recording 714 home runs across 22 seasons, winning seven World Series.

The greatest slugger of them all remains a hero, transcending his sport to enter America’s national conscience as a cultural icon.