https://www.auntyflo.com/spiritual-meaning/smudgingSmudging
The use of sage or another herb to cleanse a person or area by burning the sage and waving the smoke around.
A blessing done to the forehead with a smudge of oil and annotation. Smudging is the act of cleaning up the physical space of a person, place, thing or situation using some kind of cleansing tool, herb, oil or sound.
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This is an art which has been commonly practiced in the native American traditions as well as ancient European traditions. The theory behind it is that when practicing magic, or attempting to contact someone or something which is viewed as higher than ourselves, we must communicate in a cleansed and pure environment.
To do so, we have to quite literally clean up the space. Some of the more common ways of accomplishing this task is to waft sage throughout the home or whatever needs to be cleaned. One can also use salt in an absorptive function because it absorbs negative energy over time.
Some who have relatively bad allergies to smells will instead use the sound of a bell or a singing bowl to break up the negative energy, thus cleaning it in preparation for their sacred works.