Read "The Swan flies away" and answer the question.

The Swan flies away

The Swan Will Fly Away All Alone,
Spectacle of the World Will Be a Mere Fair
As the Leaf Falls from the Tree
Is Difficult to Find
5 Who Knows Where it Will Fall
Once it is Struck with a Gust Of Wind
When Life Span is Complete
Then Listening to Orders, Following Others, Will Be Over
The Messengers of Yama are Very Strong
10 It’s an Entanglement with the Yama
Servant Kabir Praises the Attributes of the Lord
He Finds the Lord Soon
Guru Will Go According to His Doings
The Disciple According to His!

Kabir

In lines 3-4, the speaker uses the word "Leaf" as a metaphor for _____.
knowledge that has been lost
randomness in the world
a human being who dies
a search for life’s answers