Austin's assiduous and scrupulous attitude towards the research astonished me in a great extent. He was also talented at the linguistic analysis and very perceptive to catch the main issue from the complexity. To read this book, you probably need to draw a model to effectively understand Austin's theory.
Have been using a set of basic terms, like sovereign, command, sanction, subject and duties, John Austin tried to redefine positive law in this book. Lecture 1 is about the basic definition of law of Austin. He referred to utilitarianism which he used as the main tool to analyze his theory in the next three lectures. In last two lectures he fell law into 4 categories, divine law, positive law, positive morality and law metaphorically or analogically so called. Subsequently he set out his idea of An Independent Political Society and Habit of Obedience which is supposed to be the bedrock of his theory of law.