This bestselling graduate quantum mechanics textbook is now available in a re-issued and affordable edition. The text first teaches how to do quantum mechanics, and then provides a more insightful discussion of what it means. The authors avoids the temptation to include every possible relevant topic, instead presenting readers with material that they can easily focus on in a complete treatment with few distractions and diversions. Fundamental principles are covered, quantum theory is presented, and special techniques are developed for attacking realistic problems. The innovative two-part coverage is entertaining and informative, organizing topics under basic theory and assembling an arsenal of approximation schemes with illustrative applications linked closely to the text.