Book: Of Sweat and Blood

The Book Of Sweat and Blood reads as follows:

Of Sweat and Blood

A Veil hangs between the world men see and the one they cannot. This Veil blocks the dead from the view of the living, and the living from the view of the dead. Some mages can break through this Veil and communicate with the dead, or else summon them to the World of the Sun for short periods of time. This is the art known as necromancy.

The dead can also break through the Veil and enter the world of the living on their own. Yet, unlike the necromancers, in doing so they are not driven by reason and will, but by a thoughtless, irrational need. This need arises from powerful emotions such as regret, longing, or wrath. Very often these emotions gain their power by seeing invested in a material object by the dead individual while he or she still knew life. The objects most frequently so endowed? Wedding rings, favorite toys - or the instrument used for the crime which sent the returned individual to the other world in the first place.