Hundreds of letters and photographs that tell the story of Pope John Paul II's close relationship with a married woman, which lasted more than 30 years, have been shown to the BBC.
The letters to Polish-born American philosopher Anna-Teresa Tymieniecka had been kept away from public view in the National Library of Poland for years.
The documents reveal a rarely seen side of the pontiff, who died in 2005.
There is no suggestion the Pope broke his vow of celibacy.
