translation.en: I finally got around to calculus as a 32-year-old tenured professor at Harvard, where I sat uncomfortably in classes with undergraduate students, little more than half my age.
translation.zh: 在我已是32岁的哈佛大学终身教授时， 我才和比我年龄一半多点的本科生很不舒服地坐在一起， 学习微积分．