What do you hunger for so much that no matter how hard you try, your appetite never seems sated? Is it food like chocolate or French fries? Hugs and kisses? Approval from others? For me, this is an easy one: knowledge. I love learning about all things history and psychology. A day that passes without learning something -- a new word, a new phrase, about groundbreaking research in consumer psychology, and so on -- feels like a day wasted. Nothing in this world can extinguish my intellectual curiosity. While everyone has their reasons for lamenting the fact that life is short, mine include the harsh reality that we can only learn so much during our limited time on this planet. To me, few things are as enriching as becoming more knowledgeable, more intelligent, more erudite. Whether it's learning how to use a formula to solve a mathematical problem or being able to expound on significant historical events, it feels great to "get" something -- and it's...