( CNN ) -- Pope John Paul II used to beat himself with a belt and sleep on a bare floor to bring himself closer to Christ , a book published Wednesday says . The late pope had a particular belt for self-flagellation and brought it with him to his summer residence , according to the book , `` Why he is a Saint : The True story of John Paul II . '' `` As some members of his own entourage were able to hear with their own ears , both in Poland and in the Vatican , Karol Wojtyla flagellated himself , '' the book says , using the name the pope was given at birth . `` In the closet , among the cloaks , a particular pant-belt hung from a hook , which he utilized as a whip and one which he always had brought to Castel Gandolfo , '' the book says . The book was written by a Vatican insider , Slawomir Oder , with Italian journalist Saverio Gaeta of the Catholic weekly Christian Family . Oder is head of the Vatican committee investigating whether John Paul II should be declared a saint . John Paul died in 2005 . The evil albino monk in Dan Brown 's `` The Da Vinci Code '' may be the best-known example of self-flagellation these days , but the practice is not unusual in Catholicism -- or nearly as extreme as it is shown in the movie . `` When members or former members [ of Opus Dei ] see the monk go at it in the movie , they just burst out laughing , it 's so nutty , '' said the Rev . Michael Barrett , a priest of the Catholic Opus Dei sect . In actual Catholic self-flagellation , `` there is no blood , no injury , nothing to harm a person 's health , nothing traumatic . If it caused any harm , the Church would not allow it , '' he wrote on Opus Dei 's Web site when the movie came out in 2006 . `` This voluntarily accepted discomfort is a way of joining oneself to Jesus Christ and the sufferings he voluntarily accepted in order to redeem us from sin . 'The Da Vinci Code 's ' masochist monk , who loves pain for its own sake , has nothing to do with real Christian mortification , '' Barrett said . Mother Teresa is among famous Catholics who self-flagellated in some way , Barrett said . Catholics are not alone in choosing to inflict pain on themselves for religion reasons . Some Shiite Muslims lash themselves until they bleed when marking the mourning period of Ashura , while fasting is practiced by people in several religions , including Jews on Yom Kippur , the day of atonement . David Gibson , a journalist who worked for Vatican Radio when John Paul II was pope , pointed out that the pontiff wrote an apostolic letter -- essentially a papal position paper -- on suffering in 1984 . `` Christ did not conceal from his listeners the need for suffering . He said very clearly : 'If any man would come after me ... let him take up his cross daily , ' `` the pope wrote , quoting the Gospel of Luke . Jesus , the pope wrote , `` suffered in place of man and for man . Every man has his own share in the Redemption . Each one is also called to share in that suffering through which the Redemption was accomplished . `` In bringing about the Redemption through suffering , Christ has also raised human suffering to the level of the Redemption . Thus each man , in his suffering , can also become a sharer in the redemptive suffering of Christ , '' says the letter , Salvifici Doloris , On the Christian Meaning of Human Suffering . `` John Paul was a product of a very Old World Polish Catholicism , '' said Gibson , who now writes on religion for Politics Daily . `` He was a very disciplined man and a very rigorous man in his personal spirituality , '' he said . The authors of the new book clearly approve of any whipping the pope did of himself , he added . `` Even though it 's going to weird people out , it 's obviously seen by his postulators as a sign of his holiness , '' he said , using the technical term for the person who investigates a person 's qualifications for sainthood . He said the idea is not as bizarre as it might sound to contemporary ears . `` The idea of fasting , renouncing something , giving up your Starbucks latte so you can send money to Haiti -- you ca n't simply look down your nose at it without rejecting a lot of other ideas about self-sacrifice , '' he said . The authors of the book based it on interviews with 114 `` witnesses '' and access to unedited documents in the Vatican 's archives , according to the publisher , Rizzoli . The book is available only in Italian , but the publisher is having it translated into Polish and other languages .
`` Why he is a Saint : The True story of John Paul II '' also says he slept on a bare floor . Pope used `` a particular pant-belt '' to beat himself , book says . John Paul wrote an apostolic letter on suffering in 1984 . Journalist compares flagellation to fasting or other forms of self-sacrifice .