The Mighty Tree

Like a mighty tree, indeed, is a man;
His hairs are the leaves and his skin the outer bark.

From his skin blood flows as sap from the bark;
Therefore it flows from pierced [skin] as sap from a tree that is struck.

His flesh is the sapwood, his sinews are the fibres, undoubtedly;
His bones are the inner wood and his marrow is like the pith.

When a tree is felled it shoots up from its root again with a new form;
From what root does a mortal rise when he is felled by death?

Do not say "from semen", for that is produced from the living.
Like a tree sprouting from a seed, after death it is soon born again.

If a tree is pulled up by its root, it will not sprout again.
From what root does a mortal rise when he is felled by death?

[You say:] Already born, he is not to be born [again],
[I ask:] Who could create him again?
Brihadaranyaka Upanishad 3.9.28.1-7