The Legend of the Four Thieves - Truth

marseilles plague doctor with mask
The usual story declares that a group of thieves during a European plague outbreak were robbing the dead or the sick. When they were caught, they offered to exchange their secret recipe, which had allowed them to commit the robberies without catching the disease, in exchange for leniency. Another version says that the thieves had already been caught before the outbreak and their sentence had been to bury dead plague victims; to survive this punishment, they created the concoction. The city in which this happened is usually said to be Marseille or Toulouse, and the time period can be given as anywhere between the 14th and 18th century. 
An alternative theory says that "four thieves vinegar" could be a corruption of "Forthave's vinegar", a concoction sold and invented by one Richard Forthave. (Published in a brief article in The Mirror of Literature, Amusement, and Instruction.)
Four Thieves Vinegar was a concoction of vinegar infused with herbs, spices or garlic that was believed to protect users from the plague.^
This specific vinegar composition is said to have been used during the black death epidemic of the medieval period, to prevent the catching of the plague.
Ingredients of Marseilles Vinegar as seen in The Scientific American Cyclopedia of Formulas: Partly Based Upon the 28th Ed. of Scientific American Cyclopedia of Receipts, Notes and Queries
Early recipes for this vinegar called for a number of herbs to be added into a vinegar solution and left to steep for several days. The following vinegar recipe hung in the Museum of Paris in 1937, and is said to have been an original copy of the recipe posted on the walls of Marseilles during an episode of the plague:
Take three pints of strong white wine vinegar, add a handful of each of wormwood, meadowsweet, wild marjoram and sage, fifty cloves, two ounces of campanula roots, two ounces of angelic, rosemary and horehound and three large measures of camphor. Place the mixture in a container for fifteen days, strain and express then bottle. Use by rubbing it on the hands, ears and temples from time to time when approaching a plague victim.


Plausible reasons for not contracting the plague was that the herbal concoction contained natural flea repellents, since the flea is the carrier for the plague bacillus, Yersinia pestis. Wormwood has properties similar to cedar as an insect repellent, as do aromatics such as sage, cloves, camphor, rosemary, and campanula. Meadowsweet, although known to contain salicylic acid, is mainly used to mask odors like decomposing bodies.
Another plausible reason for its effectiveness may be the antimicrobial properties of its constituents. Scientists have found wormwood, meadowsweet, wild marjoram, sage, cloves, campanula, angelica, rosemary, horehound and camphor to have antimicrobial properties.* 
Another recipe called for dried rosemary, dried sage flowers, dried lavender flowers, fresh rue, camphor dissolved in spirit, sliced garlic, bruised cloves, and distilled wine vinegar.
Marseille Vinegar Recipe: Rosemary, Sage, Lavender, Rue, Camphor, Garlic, Cloves, Distilled White Vinegar
Modern-day versions include various herbs that typically include sage, lavender, thyme, and rosemary, along with garlic. Additional herbs sometimes include rue, mint, and wormwood. It has become traditional to use four herbs in the recipe—one for each thief, though earlier recipes often have a dozen herbs or more.


^See Albert Allis Hopkins, The Scientific American Encyclopedia of Formulas: partly based upon the 28th ed. of Scientific American cyclopedia of receipts, notes and queries (Munns & Co., Inc., 1910), 878; Henry Power & Leonard William Sedgwick, The New Sydenham Society’s Lexicon of Medicine and Allied Sciences (New Sydenham Society, 1881); Matthieu Joseph Bonaventure Orfila, Practical Chemistry; Or, A Description of the Processes by which the Various Articles of Chemical Research, in the Animal, Vegetable, and Mineral Kingdoms, are Procured (Thomas Dobson and Son, at the Stone house, no. 41, South Second Street., 1818), 2; Thomas Byerley & John Timbs, The Mirror of Literature, Amusement, and Instruction; (Volume 12, 1828), 89; J.A. Paris, Pharmacologia (Volume 2, 1825), 18.

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P, Denev; M, Kratchanova; M, Ciz; A, Lojek; O, Vasicek; D, Blazheva; P, Nedelcheva; L, Vojtek; P, Hyrsl (2014). "Antioxidant, Antimicrobial and Neutrophil-Modulating Activities of Herb Extracts"Acta Biochimica Polonica. 61 (2): 359–67. doi:10.18388/abp.2014_1907PMID 24945135.

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