This book is a work based on the authors more than 30 years of legal teaching experience. It introduces the basic structure of law to law students and the general public in concise and plain language. Starting from the basic way of legal creation, the author disassembles the laws of different departments horizontally, extracts the basic elements of legal composition, analyzes how these elements interact and exert their effectiveness in statute law, case law and regulatory rules, and further reveals the legal factors. how it gets complicated, and the errors and confusion that arise from it. Based on his own experience, the author clarifies the common elements contained in the complicated legal rules in a simple way, and frankly points out which ones are crucial, which ones are superficial, and which ones cause mistakes and omissions. The whole book uses a deconstructive approach of positivism to help beginners straighten out their legal thinking and open a door to understand the essence of law.