Man is on earth as in an egg.
Our envy always lasts longer than the happiness of those we envy.
Heraclitus somewhere says that all things are in process and nothing stays still, and likening existing things to the stream of a river he says that you would not step twice into the same river.
Everything flows and nothing abides. Everything gives way and nothing stays fixed.
There is nothing peranent except change.
Man is most nearly himself when he achieves the seriousness of a child at play.