BY ROBERT EIDELBERG IN HIS UNIQUE SERIES OF INTERACTIVE BOOKS ON KNOWING, THINKING, AND CREATIVE WRITING: WE DON’T KNOW: The Book of Non-Knowledge and the Volume of Our Current Ignorance GOOD THINKING: A Self-Improvement Approach to Getting Your Mind to Go From “Huh?” to “Hmm” to “Aha!” PLAYING DETECTIVE: A Self-Improvement Approach to Becoming a More Mindful Thinker, Reader, and Writer by Solving Mysteries EVIDENTLY, MY DEAR ARMCHAIR DETECTIVE: Solving Ten Classic Mysteries Together With Their Celebrated Sleuths “WHO’S THERE?” IN SHAKESPEARE’S HAMLET