Warren Buffett often said that reading this book is the greatest investment that he has ever made, and it’s not difficult to see why. Buffett even specifically mention that chapter 8 and 20 are the most essential ones to understand how investing and the market work.
But if you want to learn about the very essence of the book, chapter 14 is where the real gem is. This is where the core Graham principles are presented, which the commentary on chapter 14 (as well as chapter 18 and its commentary) prove that this principles can stand against time for more than 3 decades.
This book to investing is like The Art of War by Sun Tzu to warfare, or The Origins of Species by Charles Darwin to evolution. An absolutely vital book to read.