WHAT'S the difference between dream and delusion?
Was Don Quixote a sad old man just because he reckoned he was fighting a dragon - when the reality was he was taking his sword to a windmill?
Is it wrong to indulge the Don Quixotes of this world, just because their thoughts are a little fuzzy?
That's the theme of this week's Oran Mor play, Don Quixote, running as part of the Classic Cuts Season.
But it's not the Don Quixote we know of from the Miguel de Cervantes story.
This time around the action moves from the 17th century La Mancha to contemporary times, set in a large house outside Glasgow.
It tells the story of Mr Quentin (played by James Smillie), an old man who wakes up one morning - and although he doesn't quite see a windmill outside his window, he does see a windfarm.
AND his mind, at the sight of it, goes off into wild imaginings.
His nephew (Scott Miller), the Sancho Panza-like character, is all caught up in the opportunism of youth, and becomes angered and frustrated by the actions of the older man.
It takes a young female care assistant to bring some calm to the confusion.
Natalie Toyne plays the Dulcinea character, the love of Don Quixote's life. Except that this time around the 'love' takes a veery different form.
"The nephew doesn't want to indulge his uncle at all," explains Natalie. "And he has the attitude that if this ever happens to me, shoot me."
The care worker is more sympathetic. Indeed, she regards Mr Quentin as loveable, funny and warm.
She can't help but be captured by the older man's whimsy.
"The play is about this dilemma of how we see people who are drifting into this state," adds Natalie.
"We do tend to put people in boxes, but the idea of the play is to open all this out. What's delusion - and what's harmless daydreaming?
"Are we not allowed to have dreams as we get older, just as we did when we were kids?"
But of course dementia can capture the mind, it can take it off in directions it would never otherwise have gone.
Yet, society still has to care for the sufferer, still has to try and understand where the mind has drifted off to.
"It's also a love story," says Natalie of the Ben Lucas adaptation, directed by Lu Kemp.
"I don't want to give too much detail away, but there is a lovely twist in the play I think audiences will really enjoy."
Natalie plays the part in her own accent. She's South African, having grown up in Durban as the daughter of a Yorkshireman.
"It's only the second time in ten years I've been able to use my own accent in a play," she says, smiling.
"And I'm really pleased.
"The director wanted a different voice to play the part of care worker, to create a different sense of character, and my accent seemed to fit.
Natalie grew up in South Africa, with her own dream of becoming an actress.
But Durban doesn't offer up theatre schools for the young aspiring thespians, either am-dram or any other such arts vehicle.
Interestingly, it was her incredible voice which took her into the arts world, becoming an acclaimed jazz singer and touring throughout Europe.
"But I really wanted to become a dramatic actress," she admits.
"And I knew there were no real opportunities for acting in Durban, so I applied to drama colleges in the UK.
"Thankfully, I was accepted by the RSAMD in Glasgow, (now the Royal Conservatoire) and I loved every minute of my time there. Now, Glagow feels like home.
"I think the people are really friendly and I love it here."
Most recently, Natalie, who studied musical theatre, appeared in the Websters Theatre production of Little shop of Horrors, playing one of the Greek chorus.
Her voice and performance was one of the reasons the show was a stand-out success.
"I really loved working on that," she says.
"But what it reminded me was how much I love being in Glasgow.
"I go away to do other work, but I always seem to come back."
NOW, she gets the chance to appear at Oran Mor, which is "fantastic".
And she gets to appear in an update of a story that seems perfect for modern times.
"Dementia has become a plague on society, but we're still unsure how to deal with it," she says.
"Hopefully the play will offer some insight and help people understand that someone suffering from the illness still has so much to offer."
l Don Quixote, Oran Mor, until Saturday.