Her soul was still mostly covered in darkness, just like when she had broken through to the Nascent Soul Realm. A small ice hill reached the edge of the darkness, and an illusory, infant version of herself sat holding a scythe on that hill.
The infant had its eyes closed as if it were sleeping, but tremendous amounts of energy were pumped through its body every moment to sustain its existence. The presence of this darkness, the ice hill, the earth underneath it, and the infant within her soul raised questions about the very nature of her being.
A soul is, at its very core, the essence of one's existence–both physical and metaphysical.
It is an objective view of who you are, not who you or anyone else believe you to be. At the same time, it is also a view into one's fate. A fate that they both can and can't control.
This is often represented in the manifestations that appear during the three Soul Realms in the Mortal Cultivation system.