Probably best known because of the Nativity story, Frankincense - derived from the resin of a tree called Boswellia serrata and other species of the same - has an interesting history. In Hebrew, its name is levonah, meaning "white;" in Arabic, a closely-related language, it is 'al-luban, a term referring to milk; the name of the modern country of Lebanon is derived from both. However, it came to be known as "frankincense" when crusaders - many of whom were French or "Frankish" - introduced it to Europe during the Middle Ages. The burning of the dried Frankincense resin has also played a part in the religious rites of all three Abrahamic traditions.
Frankincense is thought to be non-toxic, but when using natural herbs for therapeutic purposes - even organic herbs - prudence and caution is called for.
*Organic resin comes from India
Warning: Not to be used during pregnancy.