Book excerpt: Ever since Socrates, teaching has been a difficult and even dangerous profession. Why is good teaching such hard work? In this provocative, witty, and sometimes rueful book, David K. Cohen writes about the predicaments that teachers face. Like therapists, social workers, and pastors, teachers embark on a mission of human improvement. They aim to deepen knowledge, broaden understanding, sharpen skills, and change behavior. One predicament is that no matter how great their expertise, teachers depend on the cooperation and intelligence of their students, yet there is much that students do not know. To teach responsibly, teachers must cultivate a kind of mental double vision: distancing themselves from their own knowledge to understand students’ thinking, yet using their knowledge to guide their teaching. Another predicament is that although attention to students’ thinking improves the chances of learning, it also increases the uncertainty and complexity of the job. The circumstances in which teachers and students work make a difference. Teachers and students are better able to manage these predicaments if they have resources—common curricula, intelligent assessments, and teacher education tied to both—that support responsible teaching. Yet for most of U.S. history those resources have been in short supply, and many current accountability policies are little help. With a keen eye for the moment-to-moment challenges, Cohen explores what “responsible teaching” can be, the kind of mind reading it seems to demand, and the complex social resources it requires.