In the Medieval era, a "sigil" was a symbol associated with a particular angel or demon, which could be used to ritually summon the relevant being. Spare turned this practice on its head, arguing that such supernatural beings were simply complexes in the unconscious, and could be actively created through the process of sigilisation. In modern chaos magic, when a complex of thoughts, desires and intentions gains such a level of sophistication that it appears to operate autonomously from the magician's consciousness, as if it were an independent being, then such a complex is referred to as a servitor. When such a being becomes large enough that it exists independently of any one individual, as a form of "group mind", then it is referred to as an egregore.