Principia Intellegentia makes the case for considering the phenomenon of intelligence in humans to be entirely bound up with their individual ability to earn. It dose this by setting out a high-level description of how humans learn, and then showing how this description for many aspects of the human condition. In addition, Principia Intellegentia makes the case for applying this same description to the design of learning algorithms for automated computing machines, thereby addressing the greatest intellectual challenge of our age: the quest for artificial intelligence. This book is a scientific monograph that describes original contributions to a wide variety of fields including neuroscience, psychology, sociology, artificial intelligence, and the philosophy of science. However, it has been written in a style that makes it accessible to the intelligent mom-expert, such that it may be classified as 'popular science'. This combination invites comparison with great works of mass appel such as The Origin of species, The Golden Bought and The Structure of Scientific Revolutions.