Guardiola, who led Barca to an unprecedented six trophies last year, told a news conference on Friday he had received the book "In praise of pessimism" by French philosopher and historian Lucien Jerphagnon.
"I am serious," the 39-year-old said with a smile.
It could be considered an unusual choice given Barca's task of overturning a 3-1 deficit in Wednesday's Champions League semi-final second leg at home to Inter Milan.
Before that, on Saturday, they will attempt to defend their one-point lead over Real Madrid at the top of La Liga against basement side Xerez at the Nou Camp and play at in-form Villarreal the following weekend.
"Everything will be decided this week," Guardiola said. "It's in our hands and we cannot afford to ease off. It's a big effort, but also a quick one."
Striding into the news conference at Barca's training facility on the outskirts of the Catalan capital, dressed in a sports shirt and jeans and with the lights glinting off his closely-shaven scalp, Guardiola appeared slightly on edge.
Forward Lionel Messi, defender Daniel Alves, who is suspended for the Xerez game, and goalkeeper Victor Valdes looked more relaxed as they mingled with photographers and signed shirts outside next to an array of expensive cars, including Messi's Maserati and Alves's Bentley.
MENTAL STRENGTH
Guardiola said it was very difficult to ignore the looming Inter match and focus on the Xerez game.
"But we have to try and achieve that. We must show a lot of mental strength. We know it's going to take a lot of effort."
"It's always difficult playing between the two legs of a Champions League semi-final," he said of the Xerez match.
"For us it's very dangerous this game. We have been 11 months fighting for the league. We can't lose this chance tomorrow."
Some of the book titles listed on Barca's website on Friday would probably be more appropriate San Jordi gifts, including "Leadership Guardiola", "Let's go Barca!" and one about the club's youth programme: "Heroes of the Masia".
Guardiola noted there were several books out about him and commented: "It was good because even I didn't know I had done certain things. It's great being Barca coach."
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