This text is an excerpt from a book on investing, The Four Pillars of Investing, by William J. Bernstein explores the crucial elements for successful investing. The author emphasizes four key pillars: investment theory, financial history, investment psychology, and the business of investing. The book uses various examples, including historical financial events and case studies, to illustrate these principles. It also cautions against common investing pitfalls, like chasing past performance and emotional decision-making, while stressing the importance of diversification, low-cost index funds, and long-term strategies. Finally, the book guides readers through constructing a portfolio, considering factors like age, risk tolerance, and financial goals.