Who is Bernadette from By the River Piedra I Sat Down and Wept and what is their importance?

Bernadette was a young girl that lived in France, near Saint-Savin. She came from a poor family and worked as a hay bailer to help out with the finances. She worked near a grotto in her town and one day is faced with having to cross a cold stream on a winter day. Because she was an asthmatic, she was scared to do so. At this time, the Virgin appeared and spoke to her. Eventually the Virgin tells her to dig inside the grotto, where Bernadette uncovers a holy spring that can miraculously cures people.