Light a camphor tablet and it burns with a tall clean flame and goes out having left no ash, no soot and no residue on the plate. That property, and not the smell, is why camphor is at the centre of Hindu worship.
The arati is the waving of a flame before an image at the close of a puja, and the flame is a camphor flame. The reading given for it in the tradition is direct: camphor is a substance that becomes light entirely, keeping nothing back, and the worshipper is asked to do the same. The self burns off in the presence of the divine and there is no remainder. Devotional literature uses the image constantly, and it is one of the few ritual substances whose meaning is a straightforward consequence of its chemistry.
Camphor is also passed around after the arati so that worshippers may cup their hands over the flame and touch them to their eyes and head, taking the light as a blessing.
Beyond the temple it is a major drug. Chinese and Southeast Asian medicine use it as a warming and dispersing agent, it was central to embalming across a wide area, and its industrial history includes celluloid and smokeless powder, both of which consumed it in enormous quantities before synthesis caught up. Most camphor now sold is made from turpentine, and the ritual tablet is usually synthetic.