St. Martin of Tours is known for his kindness and generosity. The story goes that he cut his cloak in half to share with a beggar, saving the man from the cold. Every year on 11 November, many people mark St. Martin's Day to commemorate his burial on this day in the year 397 AD.
In Central Europe, it has long been customary to eat a goose to celebrate St. Martin - although no one knows the precise origins of this tradition any longer. One reason could be that Eastern churches mark this day as the start of Lent, a period of fasting. Therefore, all the food that was forbidden during Lent needed to be eaten now. Also, it was traditional in many places to celebrate and feast on the eve of 11 November with food and drink.
Yet another reason could be that farmers often paid their lords or landowners with geese, so they always had geese on their farms. This made them a natural choice for a feast.
Another plausible theory lies in the legends about St. Martin. One legend goes that the townsfolk of Tours wanted to ordain him a bishop. He was a modest man and hid in a goose pen when they came looking for him. But the loud cackling of the geese gave him away and the people found him, after which he was ordained bishop.