Shadesmar, is a plane of existence. It is the cognitive realm and binds the other two realms of existence (spiritual and physical) together.
Most people only interact with Shadesmar subconsciously through intuition or artistic expression, but Shadesmar is all around everyone all the time. It is created by the deep, profound thoughts of people and then shaped by spren.
Lay of the landEdit
Geographically it appears to be a reflection of Roshar, with its inland seas corresponding exactly to the shape of the land of Roshar. Within it are:
Shallan visits this realm when she Soulcasts because she has the inherent ability to Soulcast. Jasnah uses a fake Soulcasting fabrial in order to cover her inherent ability, and Shallan will likely have to use her broken one for the same purpose.
In her point of view, Shallan describes Shadesmar as an endless sea of tiny black beads that appear to be made of glass. The sky is black, and there is a small white sun above the horizon that seems as though it is not far away. She enters the realm above the sea of beads where flames hover 'like the tips of candles floating in the air and moving in the wind' and then falls into the sea of beads.
There is a being there with whom she must negotiate in order to Soulcast. Jasnah indicates that the more infused spheres one has, the easier it is to manipulate Shadesmar; Shallan was nearly pulled into the sea when she visited there with only one dun sphere.
Entry into this realm is granted by a type of spren that most people cannot see. Shallan can only see them in her drawings, though she can communicate telepathically with them at all times, and Elhokar Kholin can see them in mirrors. They grant access to Shadesmar to Shallan when she speaks a truth about herself; the stronger and more secret the truth, the stronger the bond between the spren and the Soulcaster. It is assumed that the being Shallan speaks with in Shadesmar is one of these spren.