Hope is at the core of human existence. It can either be an emotion or an attitude. In either case, it is a natural and basic affection of the mind. This analysis of hope will clarify the concept by dealing with its involvement in knowledge, ethics and metaphysics. Hope can lead to truth or error, depending on whether it is a presentation of probabilities by the intellect, or just a reflection of expectations from the will. In this book, a short survey of views on hope, from the history of philosophy, will be followed by an account of Schopenhauer's critical approach. Hope will be treated within his framework of optimism and pessimism, and of how it may serve as an important element in the critique of ideologies.