The use of incense as a key to unlocking the doorways to higher spiritual realms dates back not just centuries, but thousands of years. We all know that The Magi, the Three Wise Men of the Bible, brought frankincense and myrrh as gifts for the birth of the Christ child, thus marking one of the most holy events in history for billions of people. That's not surprising since the origins of incense as a substance of higher attainment had been engrained in the consciousness of humanity for at least 3,000 years before the advent of Christianity.
Frankincense, for example, is known to have been traded across the Arabian Peninsula for 5,000 years. Sacks of this resin are depicted on the walls of the Egyptian Queen Hatshepsut who reigned in around the time of 1483 B.C. Frankincense is also integral to the Ketoret, which is literally the offering of incense in ancient Hebrew religious celebrations.
The pungent, resinous incense, myrrh, was so valuable in ancient times that its value often surpassed that of gold. It was also central to the spiritual practices of the ancient Egyptians and was even part of the mummification process.
Bringing the ancient past with us, let's fast forward to the present and talk about the spiritual significance and uses that various incenses still hold today, and which are still employed by modern pagans, Wiccans, other profoundly mystical traditions. Just a few of the most common incenses today are jasmine, copal, rose, sage, kewda, sandalwood, and mogra -- but again, that's just a few! The fragrances produced by these incense essences are believed by some to attract specific aspects of certain deities or perhaps vibration frequencies of a specific kinds of spiritual energy. Note that the specific kind of manifestation, and just what these energies are - specific gods, or more generalized universal powers - varies from tradition to tradition.
In some pagan practice, for example, one may employ copal both for consecration and/or to banish negative energy. In the tradition of Hoodoo, incense made from star anise is burned to increase psychic awareness and induce clairvoyance. One of the most important herbal incense types in Native American spiritual practices is sage. They use it for an array of effects, from purifying energy to emotional balancing and healing illnesses.
Many types of incense are used to attract spirit guides near to us so that we may form a closer presence or call upon their aid in our daily lives. Myrrh is a preferred go-to scent for this in a number of traditions. Many other types of incense help focus the mind in meditation.
Keep in mind that incense lore is an extremely deep field of specialty in and of itself. The sheer number of substances and the amazing variety of scents that can be obtained through the burning of incense is a specialization that few individuals have mastered completely without years of study.