Rinse lentils, place in soup kettle, cover with 8 cups of water. Let come to a boil. Cut sausage in pieces and add to lentils, cook slowly for 45 minutes. In separate pan, saute garlic, onion, celery, and carrot in olive oil; add salt, pepper, chopped tomatoes and marjoram. Cook for about 20 minutes and add to lentils. Simmer together for 10 minutes longer, until lentils and vegetables are tender.