January 7, 1844 – April 16, 1879: Age 35
On February 11, 1858, three poor girls were gathering firewood near a cave in the south of France when one of them clearly say a small beautiful lady standing in a niche in a rock. Moreover, the lady spoke to her, telling her to come back to the cave every day for 15 days. The two other girls saw and heard nothing.
The girl obeyed the vision and returned again and again, having conversations with the lady that consisted mostly of sound common-sense advice on prayer and penance. Having also told her family about the visions, however, the future St. Bernadette soon had a crowd following her to the cave every day. On day nine, the lady told Bernadette to drink from the spring that flowed under the rock and eat the plants that grew freely there. There was no spring, but Bernadette tried digging a muddy patch and drinking the filthy droplets that collected, then eating some of the plants. When the audience saw that all she had to show for this was a muddy face, most concluded that she was either lying or insane, but when, within a few days, a little spring began to flow from the muddy patch, everything changed.
People began visiting the place and drinking and washing in the water, and reports of its healing properties began to circulate.
By visit number 13 the lady asked Bernadette to tell the local priest to build a chapel there. The local clergy was quite skeptical, asking Bernadette to find out the name of the apparition. After a few visits in which this request was met in silence, the lady finally replied, "I am the Immaculate Conception".
This statement changed everything. Had she simply said "I am Mary" or "I am the Virgin" things might have been different, but the doctrine of the Immaculate Conception had been officially defined as dogma by Pope Pius just four years earlier (this was a theological issue not well known to the public, and it is very unlikely that an illiterate country girl would have known anything about it). Suddenly Bernadette's visions were linked to a philosophical development in the official Catholic Church.
By the time she was 22 Bernadette had had enough of the attention her visions attracted. She was a genuinely devout woman who liked simple things and certainly did not aspire to fame or power. She entered a convent at Nevers, 700 kilometres from Lourdes, where she worked as an infirmary assistant and later as a sacristan. Although she did ask for water from the Lourdes spring once to help her asthma (it completely cured her), she didn't ask for it when she tuberculosis.
Tuberculosis commonly attacks the lungs, but can also attack other parts of the body, including the central nervous system, lymphatic system, bones, joints, and even the skin. In Bernadette's case, it affected her right knee. She eventually died of it at the age of 35.
Calls for her beatification immediately, and as part of the investigation her body was exhumed and placed in a new casket in September 1909. Those present, who included a Bishop and two doctors as well as several members of the religious community, found that although her crucifix and rosary showed signs of oxidation, her body was perfectly preserved and had no unpleasant smell. It was washed and reburied, but exhumed again in April 1919, when it was observed that there was some discoloration of the face: this was attributed to the washing after the first exhumation. It was exhumed a third time in 1925, and relics were taken and sent to Rome. The doctor who removed the relics (what they were is not stated in any of the sources I found) noted that the skeleton and muscles in the 46-year-old corpse were perfectly preserved, including the liver, and commented that "this did not seem to be a natural phenomenon."
The face and hands were covered with a light wax mask and, upon her official beatification in June of that year (full sainthood would follow eight years later), it was sealed in a reliquary made of crystal so that all could see the miraculous body. You can, too, below.
Sources: Wikipedia, Biography Online, Catholic Online