Mesmer was the first to propose a rational basis for the effects of hypnosis.Although we now know that his notion of “animal magnetism”, transferred from healer to patient through a mysterious etheric fluid, is hopelessly wrong, it was firmly based on scientific ideas current at the time, in particular Isaac Newton’s theories of gravitation.
From a Western point of view, the decisive moment in the history of hypnosis occurred in the 18th Century (coinciding with the Enlightenment and the Age of Reason).
The work of Franz Mesmer, amongst others, can be seen as both the last flourish of “occult” hypnosis and the first flourish of the “scientific” viewpoint.
These practices tend to be for magical or religious purposes, such as divination or communicating with gods and spirits.
It’s important to remember, however, that what we see as occultism was the scientific establishment of its day, with exactly the same purpose as modern science – curing human ills and increasing knowledge.
At the same time, the nature of “ordinary” consciousness is better understood as a series of trance states that we go into and out of all the time.