This book presents the example of a shopkeeper being honest with a naive customer as an example of a man acting in accordance with duty, but not from duty, which this book defines as "the necessity of an action done out of respect for the law." This book argues that happiness can only be considered good by an impartial observer if the happy person has a good will, which this book identifies as the only unqualified good in existence. This book argues that "every rational being exists as an end in himself" as part of its 
This book presents the example of a shopkeeper being honest with a naive customer as an example of a man acting in accordance with duty, but not from duty, which this book defines as "the necessity of an action done out of respect for the law." This book argues that happiness can only be considered good by an impartial observer if the happy person has a good will, which this book identifies as the only unqualified good in existence. This book argues that "every rational being exists as an end in himself" as part of its formulation of the (*) "kingdom of ends." This book states that people should act only according to maxims which they can will to become universal law. Criticism of this work's obscurity prompted its author to write Critique of Practical Reason. For 10 points, name this book that first introduces the "categorical imperative," written by Immanuel Kant.
This book presents the example of a shopkeeper being honest with a naive customer as an example of a man acting in accordance with duty, but not from duty, which this book defines as "the necessity of an action done out of respect for the law.
Groundwork of the Metaphysics of Morals [or Grundlegung zur Metaphysik der Sitten; accept similar translations including Grounding for the Metaphysics of Morals or Foundations of the Metaphysics of Morals; do not accept or prompt on just "The Metaphysics of Morals" or "Die Metaphysik der Sitten"]