The Neshamah is a djinn's inner fire and is the source of all their power. Djinn have many words for fire (almost as many as the Eskimo have for snow) but this refers to the part of the djinn's center which controls their djinn power. Notably, it can be weakened by the cold. In the winter, John and Philippa Gaunt's powers were diluted by the colder weather. Even full grown powerful djinn (such as Iblis and Manco Capac) are affected by this.