The festival attracts around 150,000 visitors to mid Wales
The Hay Festival is flinging open its doors for the 21st time.
Literary, musical and political celebrities will descend on a tented village at Hay-on-Wye in Powys which becomes its temporary home every May.
Over the years it has become something of a mecca for not just of the literary kind, but personalities on a global scale.
Jimmy Carter follows Bill Clinton on the list of former US Presidents who are flying in for the event.
Other names include actresses Kathleen Turner, Doctor Who's Catherine Tate, and author John Irving.
From political circles, Cherie Booth, John Prescott and Lord Levy bring their much talked-about memoirs to Hay audiences over the next 11 days.
Jimmy Carter is the second former US president to speak at Hay
Festival director Peter Florence admits the event, which is sponsored by the Guardian newspaper and Sky Arts, has grown exponentially since it was dreamt up around a kitchen table in 1987.
Back then there were just six volunteers manning the show. From Thursday there will be 240 people on site managing hundreds of events, night and day.
But Florence insists the ethos behind Hay has not changed.
"The scale of it has grown but I think the philosophy is still the same," he said.
"The ideas is still that its something between friends, going to see writers, musicians and politicians during the day, getting together to talk about what you've seen in the day.
However, he also admits the economic implications of the literary get-together are "startling".
The festival caters to more than book lovers
"In that it's a multi-million pound thing running as a charity and a social enterprise rather than a business. It also generates about £15m of economic benefits to the community locally".
Jimmy Carter's appearance at Hay this Sunday is a nod to Florence's "abiding passion with Britain's relationship with America in politics and literature".
Now an elder statesman at 83, Mr Carter won the 2002 Nobel Peace Prize and has recently been on visits to the Middle East.
Another favourite for the director is John Irving, writer of possibly Florence's favourite ever book The World According to Garp in 1978.
There is also something of a chess theme going to Hay 2008 with Gary Kasparov talking about his fight standing up for democracy in Russia (Saturday 31 May) while fellow one-time champion Boris Spassky takes on 20 players simultaneously on Sunday 25 May.
Atonement writer Ian McEwan is also putting on the world premiere of a new opera For You - written with composer Michael Berkeley - at this year's festival.
Hay is not just Hay any more though.
It takes on an outreach function with seven satellite festivals, including two in Spain and one in Columbia, tapping into Spanish literature which Florence calls the "other great literary tongue".
This year there is another first a link up with a privately- run prison in south Wales. Events in one of the festival venues are being beamed live to Parc near Bridgend and writers will be visiting inmates there too.
Florence is passionate about spreading the literary message wherever he can.
But he says he does not want the festival enterprise to keep on growing.
"We don't want it to get any bigger. There's something about the intimacy and that is very important."