The Edinburgh International Book festival is beginning its 16-day residence in the city's Charlotte Square Gardens.
More than 800 authors from 45 countries will be appearing at about 750 events during the festival.
Festival director Nick Barley promised "an Olympics of the mind" with top authors discussing big ideas.
Half of the 12 authors long-listed for the 2012 Man Booker Prize will be appear at the festival.
Ned Beauman, Michael Frayn, Deborah Levy, Hilary Mantel, Will Self and Jeet Thayil will all showcase their work in Edinburgh.
Also appearing will be Zadie Smith, Howard Jacobson and Pat Barker.
Mr Barley told BBC Scotland: "We have had the Olympics - the joy of seeing all that sport - and I think people can now get themselves into a different mindset.
"This is an Olympics of the mind where people can come and think hard about who we are and what we are doing."
He said that in addition to intellectual challenge there would also be lots of fun at the festival.
Mr Barley said funnyman David Walliams would introduce his new book Gangsta Granny, while crime writer Val McDermid will present her first book for children My Granny is a Pirate.
The children's section of the festival also includes Jacqueline Wilson, who will give young audiences a peek of her re-interpretation of the classic Five Children and It.
Andrew Motion will be reading from his sequel to Treasure Island and Frank Cottrell Boyce from his sequel to Chitty Chitty Bang Bang.
Mackenzie Crook, best known as Gareth from The Office, and BBC Radio 2 DJ Simon Mayo will also discuss their new books for youngsters.
Interviewer Jeremy Paxman and former Chancellor Alistair Darling are among the other well-known names.
Other politicians include ex-Prime Minister Gordon Brown, who will deliver the National Library of Scotland's Donald Dewar Lecture, and First Minister of Scotland Alex Salmond, who will discuss his life beyond politics and literary tastes with Booker Prize-winning author Ian McEwan.
Many of the sessions have already sold out including Frank Close's A Race for the Higgs Boson, which will be chaired by Professor Peter Higgs, who first identified the concept in the 1960s.
On the opening day, influential journalists Ian Black and Paul Mason are sold out for their session on What Caused the 2011 Revolutions?, as are actor Simon Callow and local favourite Alexander McCall Smith.
On Sunday, the big draws include British-born Pakistani Maajid Nawaz, who was recruited into a global Islamist party and rose to its leadership before being imprisoned in Egypt.
Former Monty Python star Michael Palin will return to the festival for the first time in 25 years.