Drain and rinse the beans. In a large saucepan, cover the beans with 12 cups of cold water. Add the sage, garlic and 3 tablespoons of the olive oil and bring to a gently boil over moderate heat. Reduce the heat to low and simmer, stirring often, until the beans are tender, about 1 1/2 hours. Season with salt and pepper. Transfer the beans to a bowl, drizzle the remaining 5 tablespoons of olive oil on top and serve.