The passage of time is a continuing thing. At 18, you're going to live forever, and you are definitely not at 52, so that is a recurring topic. I still think it's the main stuff.
“A whole army, though they can neither write nor read, are not afraid of a platform, which they know is but earth or stone; nor of a cannon, which, without a hand to give fire to it, is but cold iron; therefore a whole army is afraid of one man.”