The Lourdes apparitions: Bernadette Soubirous at the grotto of Massabielle

In 1858 the grotto of Massabielle was common land on the left bank of the Gave de Pau, just outside Lourdes. People grazed animals there and dumped rubbish. Bernadette Soubirous was 14, the daughter of a poor miller's family.

Thursday, 11 February 1858. Bernadette was at the river with her sister Toinette and their friend Jeanne Abadie. As she took off her shoes to cross the water, she heard a noise like a gust of wind while the trees stayed still, then heard it again. Only a wild rose in a grotto niche moved, and dazzling light came from the dark alcove behind it. In her 1861 letter to Fr Gondrand, she described "a lady wearing a lovely white dress with a bright belt," adding, "On top of each of her feet was a pale yellow rose."

Later tellings add a golden colored cloud, a smile and a beckoning gesture. Bernadette tried to make the sign of the cross but could not lift her hand until the Lady made it first, then she prayed. "When I stopped saying the Hail Mary, she immediately vanished." She never named the figure, calling it "Aquerò." That thing.

On 14 February she sprinkled holy water, and the Lady smiled and nodded. On 18 February the Lady asked her to come for fifteen days, and word spread. About 350 people watched on 25 February as Bernadette moved on her knees and scratched the ground until muddy water appeared, and she reported the words "Go and drink from the spring." On 2 March came another request, "Go and tell the priests to build a chapel here," but Abbé Dominique Peyramale refused. By 4 March, 8,000 people stood at the grotto, with some counts above 9,000.

25 March. The Lady stopped smiling, raised her eyes to heaven and folded her hands over her breast before saying, "Que soy era immaculada councepciou," meaning "I am the Immaculate Conception." On 7 April Dr Pierre-Romain Dozous watched a candle flame touch her hand and said he "could not find the least trace of burning." The last apparition came on 16 July from across the river, when Bernadette said, "She was more beautiful than ever." Through it all, no one except Bernadette saw or heard the Lady.

The civil authorities saw public disorder. Police commissioner Dominique Jacomet questioned her on 21 February and threatened her with prison, while Imperial prosecutor Vital Dutour demanded that she stop going to the grotto, but she refused. Judge Ribes threatened prison again, and across about eight interrogations she reportedly told the same story every time. In June the grotto was barricaded and people were fined for kneeling there. It reopened in October on the order of Napoleon III.

On 28 July 1858 Bertrand-Sévère Laurence, Bishop of Tarbes, set up a commission of enquiry. It weighed Bernadette's testimony, the spring and the cures, with evidence from doctors, chemists and geologists. On 18 January 1862 the bishop judged that "the Immaculate Mary, Mother of God, really appeared to Bernadette Soubirous."

Some townspeople wanted her put in an asylum. Sceptics proposed hallucination, shaped by the 1854 dogma of the Immaculate Conception and by Pyrenean folklore. Defenders pointed to the two days she came expecting the Lady and saw nothing. Robert T. Carroll and Joe Nickell questioned the cures. Within weeks other visionaries, many of them children, were claiming visions at the same grotto.

Bernadette was canonised in 1933. Lourdes now draws about 4 to 6 million pilgrims a year. Her own view stayed modest. "The Virgin used me as a broom to remove the dust."