Pick through the dried beans and discard any shrivled or broken beans. Also watch out for tiny stones. You can use any mix of beans you like but my mix tends to inclue equal parts navy beans, pinto beans, and kidney beans. Put the beans in a large pot and add water enough to cover the beans by a good 3 inches. Cover and let soak for at least 8 hours or overnight. (alternately you can put the beans in a pot, cover with water, bring to a boil, cover and remove from heat, let stand for an hour. It yields a differnt texture but still yummy). Drain beans. Heat the oil in a large pot over medium heat. Saute the onions and garlic until the onion becomes translucent or about 3 minutes. Add the celery and carrots, saute another 2-3 minutes. Add the 8 cups of water and bullion cubes. Bring to a boil. Cover and lower heat to simmer. Simmer for 1 hour and 40 minutes. Add lentils, tomatoes, spinach, ground red pepper, oregano, and basil. Cover and simmer 20 minutes more. Both beans and lentils should be soft at this point. If they are not let them simmer longer. Add salt and pepper to taste.