Book excerpt: Beautifully written yet highly controversial, An Image of Africa asserts Achebe's belief in Joseph Conrad as a 'bloody racist' and his conviction that Conrad's novel Heart of Darkness only serves to perpetuate damaging stereotypes of black people. Also included is The Trouble with Nigeria, Achebe's searing outpouring of his frustrations with his country. GREAT IDEAS. Throughout history, some books have changed the world. They have transformed the way we see ourselves - and each other. They have inspired debate, dissent, war and revolution. They have enlightened, outraged, provoked and comforted. They have enriched lives - and destroyed them. Now Penguin brings you the works of the great thinkers, pioneers, radicals and visionaries whose ideas shook civilization and helped make us who we are.