Wash the beans, cover with water and bring to a boil; let soak 1 hour.
Drain and combine with the 2 quarts water.
Bring to a boil and cook over low heat 3 hours.
Puree half the beans in an electric blender or force through a sieve.
Return to the saucepan.
Heat the oil in a skillet; saute the onions and garlic 5 minutes.
Add to the soup with the salt, pepper and parsley.
Cook 5 minutes.