Thursday was my 30th birthday.

It was the last of the big birthdays. I know every decade after thirty is sort of a milestone in its own right, but most of the significant birthdays come before this one: 1, 13, 16, 18, 21, 25. They all measure some sort of cultural or social achievement: being born, becoming a teenager, driving, voting, drinking, being able to rent a car. And 30 is the age at which one truly reaches adulthood, whether she likes it or not.