In a large saucepan, heat the oil. Add the garlic, anchovies, olives, capers, diced eggplant and crushed red pepper and cook over moderate heat, stirring occasionally, until golden, about 5 minutes. Add the tomato paste and cook, stirring, for 1 minute. Add the canned tomatoes with their juices. Season with salt and pepper and bring to a boil. Simmer the sauce over low heat, stirring occasionally, until it thickens and is reduced to 3 cups, about 30 minutes. Season again with salt and pepper.