The Principal Thing elucidates the need for 'applied wisdom', without which man may battle ceaseless with retardation in life. It links knowledge, understanding, wisdom and applied wisdom and demonstrates how man can also be pregnant, giving birth to witty inventions, and fulfilling his purpose. The book provides appropriate answers to pertinent questions about life such as: how did I come into existence? What is my purpose of existence? Was man designed to rule man? Can any man solve all the problems of his nation? When will terror end? Why is democracy failing and the need for a modified democracy? Why Africa has remained underdeveloped and how Africa can live its purpose? Why and when will we have BREXIT leading to GEEXIT, FREXIT, and GREXIT etc? And how can man and every nation fulfill his purpose of existence. It is a guide to a fulfilled living for every man and nation.