Classical containment of spectral energy occurs only through exorcism, condemnation, incantation or any combination of these. Entity transfer associated with containment of the entity by a substance (such as an idol which binds the spirit) can be fundamentally treated as a variation of auric flow. In each case, the containing force for spirit capture is a difference of frequency. Spirit containment is of particular interest to ghostbusters, who attempt to understand and control the flow of spirits through the use of ecto containment, proton packs, and other devices.