Magic in Bartimaeus - The Planes

The Planes

There are multiple co-existing planes in the Bartimaeus trilogy. The first plane contains all physical things, while the others show magical activity. Humans can normally only see the first plane; however, magicians use lenses that allow them also to see into the second and third planes (and blearily onto the fourth). Usually, these lenses take the form of contact lenses, but magicians sometimes use them in the form of eyeglasses or monocles. Auras are emitted on the first plane, but are invisible to humans. (Spirits and cats can see them, however.) These can reveal someone's emotions or intent. Almost all spirits are able to see and change their appearance on other planes. The number of planes on which a spirit can operate depends on that spirit's power. Bartimaeus is able to see and disguise himself in the first seven planes, though the disguise is weaker on the higher planes. A spirit cannot hide their true appearance to any spirit at least as powerful as themselves, as their "true" form is revealed on a higher plane. There is a theoretical 8th plane that the demons sealed inside seven-league boots can access. According to Bartimaeus, seven planes are enough for anyone and those who operate on more are "just showing off".