Heirs to the Lost World
There are thirteen levels of the Spiritworld (called tamoanchan or ilhuicat) reaching upward from the physical surface world. The first level of the Spiritworld overlaps the physical world and can be reached through spells, especially with the aid of rituals and drugs. The highest level of the Spiritworld is inhabited by the most powerful gods, Loas, etc. These greater spirits often have control or influence over some aspects of nature. Greater spirits depend on the devotion and rituals of their worshipers to sustain them (else they will be forgotten). The lowest level is inhabited by lesser spirits. These are the easiest to contact and control.
On death, most spirits of the deceased (formed from the Teyolia aspect of the soul) go on to the Spiritworld. No one knows how to move between/among the levels of the Spiritworld while alive.
Dreams are also a conduit to the Spiritworld. Most people cannot control their dreams and are sometimes visited by spirits.