$PI I once asked a friend,

if they truly achieved financial freedom,

what kind of life would they want to live.

They said, I'd just want to carry a backpack every day,

and audit classes at the university.

Listen to white-haired professors lecture on mathematics, philosophy, and art,

those things unrelated to making a living, yet truly fascinating.

Sitting in the last row of the classroom, with wind outside the window,

someone speaking slowly at the podium, while I listen quietly,

and take careful notes.

Not for grades, not for diplomas,

not for promotions, nor for publications.

Only for that moment of sudden enlightenment: so that's how it is.

After class, go to the cafeteria for a hot meal,

and ponder while walking how much more I understood about the world today.

Until now I still believe,

this is probably the most pure,

the most solid happiness one can have in a lifetime.