In "Rational Expectations," William Bernstein embarks on a meticulous journey to demystify the complex world of quantitatively based asset allocation, presenting a masterclass intended not for the novice investor, but for those with a seasoned grasp of financial theories and quantitative abilities. Bernstein challenges the conventional wisdom of market timing and stock picking, urging investors to elevate their understanding of finance before attempting to navigate the intricate dance of asset allocation. This book is an essential beacon for those ready to refine their approach to investment, armed with a robust understanding of risk premiums, standard deviations, and a reverence for financial legends like Irving Fisher and Benjamin Graham. Bernstein's work stands as a pivotal contribution to the Investing for Adults series, offering a rigorous, yet accessible exploration of the principles that should guide the sophisticated investor's strategy. "Rational Expectations" is not merely a book; it is a comprehensive toolkit for the investor who aspires to navigate the financial markets with precision. Through a blend of empirical evidence and practical advice, Bernstein escorts readers towards a more enlightened path of investing, one that eschews the allure of quick gains in favor of a disciplined and rational approach to asset allocation. This volume is an indispensable guide for anyone poised to master the art of investing, providing the clarity and insight needed to make informed decisions in an unpredictable market.