Soak beans overnight.
Drain and bring to a boil with fresh water covering the beans by about 2 inches. Lower heat and simmer uncovered for about 1 hour or until soft but not falling apart, reserving cooking liquid.
Meanwhile, in a large, heavy saucepan, sauté the sausage, onions and garlic in olive oil until the onions are translucent. Add the tomato sauce. Add the herbs, salt and pepper to taste and simmer 1 hour.
Add the borlotti (or butter) beans with their cooking liquid and simmer for another hour.
Serve alone or over soft polenta.