Sometimes I am asked what might seem to be a straightforward question, and yet I hesitate to answer. The reason is often that I am torn between an oversimplification that trivializes the topic under discussion, and a full explanation that goes well beyond the knowledge and experience of the person (often a student) asking the question. And sometimes middle ground is very hard to find. I recently stumbled on this video of Richard Feynman explaining why “Why?” can be so hard to answer. This one might enter the pantheon of my First Day Videos for students.