Four letters and a one word
Simply it's "LIFE" as I heard
Made up of a thousand explanations
And it's the start and also an end of a generation...

Sweet, Bittersweet, and also Sad
Permanent happiness! Are you mad ?
Poor or Rich! Does it forever last ?
Yes. It's the LIFE that flows so fast...

Starts with a smile. Ends with sorrow.
Comes with nothing. Nothing carries when you go.
Stops everything. And come home no more.
King of the Jungle, even Lion ceases his ROAR..!