Invocation and evocation are English words that are often used interchangeably. They are both derived from the Latin word vocare, which means to call forth. Both words can deal with summoning interaction with non-human entities. Yet, many people, especially those with knowledge of the occult, believe there are differences. These are generally based on how an entity is summoned and which entities are being dealt with.
In most cases, the words invocation and evocation are used in conjunction with actions that deal with peoples’ beliefs. Many people limit the use of these words to occult practices. According to their proper definitions, however, this does not have to be the case.
The first notable difference between evocation and invocation involves the distance between the entity that is being called forth and the person who is doing the calling. With an evocation, a non-human entity is summoned, but is not linked to the caller. The entity remains in an outer area. The energy that is used to summon the entity is also believed to be derived from outside of the caller.
With an invocation, the caller becomes a medium. The entity that she summons is meant to come forth within her. This person is generally believed to use inner resources or energies to allow this to happen.
When the process of invocation is successful and a non-human entity is acting through a person, a number of changes are believed to be possible. The person’s voice, for example, may be altered. Her physical appearance and demeanor may change. However, many who claim to have had such experiences say they are fully aware while the entity is acting through them.
Another difference between evocation and invocation involves the types of beliefs they are associated with. Evocation is generally only associated with the occult. Entities that are evoked are usually those that are perceived as being rivals to a heavenly God. These could include the devil or his demons.
Invocation can be associated with either type of belief. Heavenly entities such as Allah or angels are often believed to be invoked. They may be summoned by way of prayer to act through their subjects.
Law is another area where both of these words can have relevance and may be confused. In legal terms, an invocation involves summoning something from another case. This could be documents or physical evidence. An evocation involves transferring a case from a lower to higher court. If a case, for example, is removed from a district court and taken to a supreme court, it has been evoked.