the Shadow of which you speak exists in you, as well. It is not so large a component as exists in me, but it is unfettered.” He must have seen her expression with one of his floating eyes, because all she could see was his back and he didn’t have eyes in it. “The Shadow in you is slight and unrestrained. In me, it is contained, confined. It is a necessary component of my existence. It gives me…flexibility.”
Sanabalis said in "Cast in Fury", "living things—they are not one thing or another—they are shaped by forces that are outside of the words that the Old Ones spoke. There is, in them, some element of the darkness—some element of chaos.” He was explaining that Leontines started as animals, who had an element of chaos in them, and then the Old Ones spoke Words to them to awake them.
It seems to me that Shadow/chaos is what allows the mortal races to be sentient without True Names. It's also what allows them to age and die. Gilbert's is just contained differently, maybe as an earlier prototype.
