Famous photo of Einstein with his tongue out.
Albert Einstein loved this image so much he requested multiple copies to send to friends.
  • Albert Einstein's most iconic photo of him sticking out his tongue was almost lost to history.
  • Editors hesitated to release it because they feared the expression downplayed his eminence. 
  • Author Mike Rucker explains how Einstein's fun and curious nature played to his greatness.

The following is an excerpt from Mike Rucker's new book, "The Fun Habit: How the Pursuit of Joy and Wonder Can Change Your Life."