Four Thieves essential oil blend Originally developed in the Dark Ages in the midst of the bubonic plague, legend has it that four thieves in France took to stealing valuables from the corpses of plague victims, and even making a few of their own, killing off the afflicted before their illness ran itís course. Yet, despite repeatedly being in close contact with the plague, the thieves somehow managed to evade the disease themselves. Eventually, the rogues were caught and sentenced to burn at the stake. In the hopes that they could ease their sentences, the four thieves divulged the secret that kept the Black Death at bay. The secret? Every time before one of their expeditions, they would wash themselves in a special blend of essential oils and then breath through masks saturated with the ointment. After this revelation the thieves were relieved of their sentence and instead were hanged.