When the outer life is stripped and burned down to almost nothing, a remnant survives in the body, and that surviving core is the imperishable spark that no wasting away can consume. The tree that loses every leaf and yet holds its living substance in the trunk and root is the human form stripped of its seasonal show, keeping the sap of spirit hidden inside the standing wood.
The holy seed is that inner substance, the seminal essence that carries the whole tree folded inside itself. When everything else falls away, what remains is the small hidden germ that can grow the whole life again, because the true substance of a person was never in the leaves but always in the seed.
Teil tree and oak: the human form stripped of its outward show, holding the living sap of spirit hidden in the standing trunk
Leaves: the outer seasonal life of the personality that falls away in the burning
Holy seed: the imperishable germ of essence that carries the whole life folded inside itself