Souls

While intangible, those who claim to have 'seen' souls describe them as inviting and familiar. Maybe it looked similar to your partner, maybe it just smelled like the food your mother used to bake. There seems to be no set distinctive look to souls, but those who bear them are oft recounted as being homely or amicable.

Souls can be found anywhere, although they are rare. However, the safest bet is most certainly ruins from the old age. Since souls do not circulate anymore, some seem to stagnate here. Otherwise one could look in graves or battlefields.

It is thought that God created souls when it was still alive. It was a bridge between divinity and mortality.
Old legends detail the myth of God's hunger for stories being the reason for souls. They would, after their mortal form had passed, visit God to share what they had experienced. Simply to be recirculated and fulfill the purpose of another body.

This, could be considered rumors and myth. What is known, is souls share a potent weight in the use of Verve. It quells the terror that Sublimity holds, and makes Verve palatable and welcoming.

It is true though that souls do no circulate anymore. Very few people hold a soul within them. Educated mages seek them out to gain an advantage in their arcane studies, while Fey are granted souls on the Court of Daggers's whim. The one species that seem to all harbor a soul are Harvesters, specially made by their creator Arrosé. These souls do not belong to the ones crafted by God. These are something new entirely.

Dreaming

The connection between souls and dreaming is somewhat well known. It is considered a requirement. Based on the connection it once bore to God, souls are what allowed a person to enter dreams. The Golden Tapestry's worshippers have sought to dismantle this notion, by introducing dreaming to common folk. This has been met with resistance.

Verve

A soul is indisputably a connection between mortality and divinity. Mages have learnt over the decades, the importance of bearing a soul. It allows them handle the effects of Verve found in the world, so called sublimity. Furthermore, it let's them resist the disorientation that sublimity imposes on casters.

Knowledge

A sect of mages have learnt that souls can harbor memories, before it is cleansed and cycled. As all magic practitioners know, knowledge is power. Learning the memories of a fighter, or even better, a mage, could be the key to unlocking magic's doors. Some lunatics have gained all their knowledge of magic simply through soul gleaning.