Drain the beans and put them in a saucepan covered with cold water, add sage leaves and two garlic cloves, 1 tbs. of E.V.O.O. Bring to boil and then, gently simmer for about 1 hour, remove the foam that comes up and add salt when they are almost cooked. Discard the sage and purée half of the beans.
Meanwhile, in a stockpot, heat the oil. Add the onion, garlic, celery, leeks, and carrots and sauté until they are clear. Add the rest of the vegetables and season with salt, pepper and the tomato paste. Stew for about 10 minutes, then add the stock, add the pureed beans and basil, and add hot water, if necessary. Simmer for about 1 ¼ hours.
Toast the bread slices and rub them with garlic. Place the bread in a heavy-bottomed large pan and pour ladles of soup together with the remaining whole beans. Drizzle with extra virgin olive oil and simmer, covered, on a low fire for about 15minutes. Serve with a generous drizzle of extra virgin olive oil in a large soup bowl.