I like public transportation. It leaves me free to watch people. The other day when I took the bus to Harvard Square, which I can pick up at the end of my block--I take the #77--I saw a young woman reading Aristotle with her iPod plugged in; I wondered what kind of music was streaming into her head. She was dressed for summer--sandals, sleeveless dress. Her dark hair was swept up from her neck, and her legs were bare. Next to her on the seat was a plastic shopping bag; printed in silvery letters across the bottom, a quote from Longfellow: "Thy fate is the common fate of all,/ Into every life a little rain must fall." There were silvery raindrops on the transparent bag. She may be taking a course at Harvard's summer school, I thought. Not once did she look up from her book.