The Other Place is the home dimension of all demons. To its residents, it is a realm of peace and healing in which there is no matter but infinite 'essence', which is described as a mass of swirling colours with no borders or boundaries, somewhere between gas and liquid. Time runs at a different rate in the Other Place compared to the human world, although it is not made completely clear in the Bartimaeus Trilogy exactly what the relationship between the two timescales is.
In the Other Place, all demons are one, and so their collective essence is a single conscious entity. This allows demons to heal from damage sustained in the human world, while also putting the exact mechanics of the Other Place beyond the reach of genuine human understanding. Human consciousnesses that visit the Other Place require something to focus their consciousness on and are able to impose their will to a certain degree on the essence of the Other Place, molding it to specific shapes. Although demons are much better at this than humans, and it does not apparently cause them any harm. However, they prefer not to do it, and appear to actively resent outsiders attempting to impose order upon their realm.
Apparently, the circle(s) drawn around the pentacles in which magicians stand whilst summoning demons from the Other Place are a method of focusing essence drawn from Other Place into a single finite spot; specifically since, as noted by Kitty on returning from the Other Place, there is a distinct difference between the Other Place and the physical realm. In the Other Place, you are everywhere at once, sometimes seeing things from several angles at the same time while on Earth you are only in one place at one time and can only see what is in front of you.
During summoning, a magician's voice carries to the Other Place in a matter of nine seconds, where the attention of the entity being summoned is roused in seven seconds. The demon then usually appears within three seconds; resisting a summoning call results in damage to its Essence. The times taken for the processes of summoning to work are in terms of human time; it is not clear how long it takes from the point of view of demons in the Other Place.
Ptolemy's Gate is a method devised by the magician Ptolemy of humans visiting the Other Place, although it is dismissed by modern magicians as little more than fanciful nonsense. In fact, as Nathaniel describes it, the procedure is 'simplicity itself'.
- The magician reclines in a pentacle - he must sit or lie since his body will collapse at the moment of transfer. No candles, runes or other barriers are used as these hinder the return of the magician to his body; Ptolemy suggests breaking the circle symbolically to help this process.
- The magician closes his eyes and shuts his mind to outside stimuli, and then inverts the basic summons, using his own true name in place of the demon's and reversing directions, e.g. 'to come' becomes 'to go'.
- Then, the name of a benevolent demon is called 3 times; if the demon is willing to assist, then the Gate is opened and it is possible, though still hazardous, for the magician's consciousness to make the journey into the Other Place.
- The magician puts on a silver or iron amulet, used to protect oneself from mean spirits.
A few hazards are:
- The said magician has to adopt a form in The Other Place
- The magician is slightly unwelcome.
- It is damaging for the magician's health, as the body is basically dead when the magician is in The Other Place.
- The body is unable to react to anything, so the body must be in a safe place so nobody can take advantage of the lack of response.
Ptolemy held that any connection between the Other Place and the physical realm must be there for a reason, perhaps so that eventually, humans and demons would come to be of mutual benefit to each other. Bartimaeus, on the other hand, views this as 'utter balderdash', thinking that 'what little interaction' there is between worlds is nothing but a 'cruel aberration...which should be terminated as soon as possible.'