The Madonna Bianca festival in Portovenere, Italy happens every year on Aug. 17, and it’s an evening of beauty, light, and music in honor of the village’s patron saint. But what exactly is this ceremony, and why has it endured for hundreds of years? The answer lies deep in Italian culture and Roman Catholic faith.

The story of Madonna Bianca begins on Aug. 16, 1399, when the entire region of Portovenere was under French occupation and was suffering from the plague, according to Discover Portovenere. During this time, a local pious man known only as Lucciardo knelt in front of a painting of the Virgin Mary to pray for his village. During this time, Lucciardo is said to have looked up to see this painting suddenly light up in a bright, white light — which is why it is now called the "White Madonna," or Madonna Bianca.