Conjuration, or conjuring, is the act of evoking spirits by means of ritual formula or words of power. In ceremonial magic these spirits are commanded to manifest within the triangle on the floor of the Temple (the triangle being a symbol of manifestation). Usually incense or smoke, or some other “manifesting medium,” is provided so that the spirits can be conjured to visible appearance rather than remaining unmanifested in the astral world. A.G.H.
Drury, Nevil. The Watkins Dictionary of Magic. London. Watkins Publishing. 2005. p. 61