The ritualistic use of plant smoke stretches back to the prehistorical era and is still used, the world over, as a way of 'cleansing' the spirit. Now modern scientific research reveals that the practice may actually have life-saving implications by purifying the air of harmful bacteria.
The burning of herbs and plant resins for medicinal and spiritual purposes – so-called 'smudging' – is an ancient practice among indigenous people around the world; one increasingly adopted by Westerners. Smudging is a technology believed to unlock the 'spirits' of various plant allies to restore balance and ease to the individual or group. Some liken it to taking a 'spiritual shower,' enabling you to wash away emotional and spiritual negativity that accumulates in your body and the spaces you live.
That said, skeptics believe attributing health benefits to the burning of sage and incense reflects 'magical thinking.' The practice has even been accused of being a New Age form of cultural imperialism where 'plastic' or 'white' shamans mimic and co-opt the traditions of indigenous people their predecessors essentially conquered.