The Little Book of Common Sense Investing by John C. Bogle is a straightforward guide to passive investing and index funds. Bogle, the founder of Vanguard Group, advocates for a low-cost, long-term investment strategy that aims to capture the overall market returns. He explains the benefits of index funds, such as diversification and low fees, and highlights the pitfalls of active investing. This book is a great resource for investors looking to simplify their investment approach and achieve consistent, market-based returns.