Sally MacNamara has long told her four children that if there’s a fire in her Seattle home, they should rescue Olga first. Olga isn’t the youngest family member or a beloved pet – in fact, MacNamara has never met Olga in person. The “Olga” that is so precious to the 63-year-old online seller is a 118-year-old diary written by a woman of the same name. Beginning in 1902, the diary chronicles the experiences of a young immigrant who was raised in a strict religious environment in America. “She did not care what she wrote, which I love about her,” MacNamara says. She purchased the diary online in 2005 – it is now one of her most prized possessions.

Over the past 35 years, MacNamara has read more than 8,000 strangers’ diaries. As a child, her mother would take her “dump diving” to salvage objects – when she discovered an old, handwritten piece of paper in the trash one day, she was immediately intrigued. MacNamara’s father killed himself when she was 13 and he left behind a locked trunk of papers that has now been lost. “I didn’t want that to happen to other people, so I started collecting and keeping people’s diaries and letters,” she says. “I fall in love with people I haven’t even seen.”

At first, MacNamara bought diaries in antique shops, but when a friend introduced her to eBay in 1998, she began using the auction site to buy and sell. She has the enviously simple username “diaries”, and 8,062 pieces of feedback on her profile prove her claims about the number of personal papers she’s collected. Yet while MacNamara has more than two decades’ experience trading strangers’ secrets, her hobby has recently become more widespread. On YouTube, videos entitled “I bought a stranger’s diary” are incredibly popular – an October 2019 video racked up 300,000 views, while the video that started the trend in December 2017 has been watched by over 6.4 million people.

MacNamara’s most valuable diary was by a preacher who met the Native American leader Sitting Bull in the 1860s.

Clearly the mystery and intrigue of reading someone’s personal history can be compelling. But should we be troubled by the inherent voyeurism? Or – as Observer literary critic Kate Kellaway once said on the subject – “do people who keep diaries secretly hope someone will read them?”

Joanna Borns, 35, is a writer from New York with 10,000 YouTube subscribers. Borns first started the YouTube trend for reading strangers’ diaries three years ago – since then, she’s purchased five diaries, which cost between $26 and $52 each. “It’s interesting to see how you’re similar to a totally random stranger,” Borns says. “The voyeurism of peeking inside somebody’s private thoughts appeals to people. On YouTube, people love a story, they love a narrative, even a mundane diary can turn into a little drama.”

Borns thinks “a lot” about the “moral aspects” of her videos, and says all but one of the diaries she’s shared have been from deceased individuals. “I certainly don’t want to broadcast anyone’s personal information – I do change the names,” she says; she also avoids sharing “dark” thoughts that diarists recorded. MacNamara is also careful where diaries end up, but jokes: “When I go to heaven people will come up to me and say I’ve read their diary and I’m going to go, ‘Oh shoot, I did, didn’t I?’”

“On YouTube, people love a story, they love a narrative, even a mundane diary can turn into a little drama.”

How exactly do old diaries end up on eBay? Borns says most seem to come from estate sales. Victoria is a 58-year-old from Cheltenham who has been selling love letters and diaries online since 2004 (she has asked to be identified by her first name only). She procures diaries in flea markets and car boot sales for up to $26 and sells them on for between $39 and $78. “You go to one of these car boot sales and you find a box and it’s scruffy and insignificant and it’s wet, and you open it up and it’s a bundle of wonderful yellowing letters tied up with a ribbon,” she says, “You’re just blown away.” Her favorite diary was written by a civilian woman pilot during the Second World War – she sold it to someone in America for hundreds of dollars.

Yet, remarkably, some people sell their own diaries. On eBay, I come across one going for $260 – it chronicles the years 2011-2019 in the diarist’s life, but they won’t tell me why they’re selling. I have more luck with Marika, a 16-year-old from Poland who recently sold her cousin’s diary for $58. “We noticed that many Americans like to buy such things… My cousin said it was a good way to make some money,” says Marika. The diary is extremely fresh – it records Marika’s cousin’s life from 2019 to May 2020. “She didn’t let me read her diary. She would not like me to know her secrets,” she says. “However she doesn’t mind if a stranger living on another continent reads it. They will probably never meet.”

The Great Diary Project includes donations from contemporary diarists, many of whom are happy to have their diaries shared.

A man from Virginia purchased the Polish teen’s diary – who knows why? Although the trend is undeniably voyeuristic, many collectors have a grander purpose. Polly North is the 41-year-old director of the Great Diary Project. Since 2007, she has rescued more than 10,000 of them. “A lot of people have traditionally disregarded the importance of these diaries,” North says. She believes historians can learn about marginalized people via journals. Yet North also receives a huge number of donations from modern diarists, who can opt to make their journals immediately available or can seal them for decades (amazingly, most people are happy to have their diaries read and shared straight away). North’s favorite is from a “virtually illiterate” woman who was brought up in a trailer park in California and is still alive. “There’s no capital letters, there’s no punctuation… It’s stripped down, it’s raw, it doesn’t tick any conventional literary boxes, but it still achieves something that’s magical.”

“She didn’t let me read her diary.... However she doesn’t mind if a stranger living on another continent reads it.”

MacNamara has sold diaries to museums and universities. Her most valuable was by a preacher who met the Native American leader Sitting Bull in the 1860s (she sold it for $10,421). She also has the diary of a “gangster girlfriend” from 1934. Yet like North, MacNamara enjoys diaries that others consider insignificant.

“One of the greatest diaries I ever got was a 1927 diary of a man whose wife had died. I got that the year my husband was killed in a construction accident – I felt everything this man felt.” There is often tragedy in lost diaries. MacNamara has one from 2000 in which a woman suffered sexual abuse. At the bottom of one entry, she scribbled: “I really hope my life doesn’t turn out to be a storage unit.” MacNamara asked the seller where he found the diary. His reply? “Storage unit.”

I recently purchased a handful of diaries from eBay to experience the phenomenon first hand. I could smell two from the late 1940s as soon as I opened the package. It’s a scent I associate with old Asterix comics, but might be better described as the dustiest corner of an antique shop – the scent of leather and paper and of being forgotten. I also bought a series of diaries spanning from the 50s to the 90s, all written by one man.

The diaries include interesting and accidental bits of social history – I’m intrigued by talk of bible classes, mining and a scribbled “Wowee!” of shock after a cinema ticket costs our writer $2.28 in 1981. A long, thin red diary from 1992 is my favorite, simply because it begins with a list entitled “Party – 23rd Feb”. Harry and Jane, Arnold and Sue, and Roger and Pam all have ticks by their names indicating they can make it – so can Mark, riding solo. But why was David written so near the top and crossed out? I can feel the anxiety in the question mark near Alan’s name.

Diaries from estate sales often end up on eBay.

When I read a journal from 1962, I understand the appeal of strangers’ diaries. For an hour, I become engrossed by the January-May of a man named George whose personal details I will omit, but whose highly personal details I will share with you.

George began 1962 with a police summons for speeding, and throughout January he took a young woman named Penelope to the theater and cinema regularly. But there’s frequent talk of Ruth – whom he can never seem to be alone with. However, on 26 January, he “pairs off” with Barbara at Rosemary’s party. I read the tiny appointment book as if it were a romance novel. By 29 January, Jan has been added to the equation, but on 1 February Penelope dumps George.

On 22 February, George dances with a new woman named Mary and deliberately ignores Jan – the very next day, he has a theater date with Barbara. When Sandra phones two days later and the pair quarrel, he ominously writes: “No theatre for her.” By 10 March, Sandra and George have apparently reached a “mutual decision” to call things off (when were they on?). On 19 March, our hero has “a rather exciting time” with a new woman named Sue.

My favorite entry comes in the clueless scribblings of the following day: “Asked Jan if she wanted to come to the ball, but she sidled out of giving a reply. Funny girl.” We then see a botched attempt to impress Sue’s parents via the filling of a coal bucket – and suddenly Sue is canceling dates. On 2 April, I actually gasp aloud when George and Sue go to the fair and Sue declares that she has decided to go steady with Peter!

This diary is one of a handful by the same man – I anxiously flick to his last notebook, from the 1990s, to see where our diarist ends up. If you’re worried that George may have lost his player credentials with age, don’t be. A 2 May 1992 entry from a Tenerife holiday declares: “Mediocre meal booked at special restaurant, but SUPERB pair of long legs opposite me.”

Would George be happy that I read his diaries? The kind of person who records romantic entanglements might be pleased that someone would marvel at his prowess 58 years later. Still, it feels inherently wrong to share his stories (which is why, in the above retelling, all of the names have been changed). Many diaries sold online are by people who are long dead, but this isn’t always the case. MacNamara was able to reunite a daughter with her mother’s diary from 1942 – her mother was in a care home with Alzheimer’s. “They’d read it to her and in that brief moment, her memory came back to that time.”

Olga is long gone – a few years ago, MacNamara visited her grave in Wisconsin. Yet through her diary, the young immigrant girl lives on. “So many people compare their lives to the media and think they don’t have a life,” MacNamara says, “There’s no diary that I’ve read that doesn’t have an incredible story to tell. We all have a story: we will all suffer hardships, we will all have great joy. You think you’re alone in the world, but you’re not.”