Definition
In law, a mystery is a trade, art, or occupation. The term appears most characteristically in the language of apprenticeship indentures, where a master binds himself to teach an apprentice his "art, trade, and mystery" — a formulaic phrase signifying the full body of skilled knowledge and craft practice belonging to a particular calling. The word carries no sense of concealment or the unknown in its legal usage; it is a term of art denoting a skilled vocation or craft guild.
Common Language
Modern common usage (Wiktionary): Something secret or unexplainable; an unknown. Also: someone or something with an obscure or puzzling nature; a genre of fiction centered on crime or unexplained events; a religious truth beyond human reason alone.
Historical common usage (Webster's 1913): A profound secret; something wholly unknown or cautiously concealed, exciting curiosity or wonder; that which is beyond human comprehension.
The gap here is total. The legal meaning is the precise opposite of the common meaning. Where ordinary usage centers on concealment, the unknown, and the inexplicable, the legal term denotes a defined, teachable, and publicly practiced trade skill. A researcher encountering "mystery" in an apprenticeship indenture or guild document should immediately set aside every common-language association the word carries.
Common Confusion
"Mystery" in legal instruments is consistently confused with its ordinary English meaning by researchers unfamiliar with apprenticeship law. The formulaic phrase "art, trade, and mystery" appears in indentures spanning several centuries and across English and American legal practice. Each of the three words in that phrase is a near-synonym for skilled occupation; the phrase is cumulative and emphatic, not a list of distinct categories. Researchers who read "mystery" as denoting something secret or occult will badly misread the scope of a master's obligations under the indenture.
Why It Matters in Research
The primary research context for this term is historical apprenticeship indentures and guild documents, where "art, trade, and mystery" appears as a standard formula. Because the phrase is archaic and the word "mystery" has so thoroughly shed its occupational meaning in modern usage, it creates a consistent comprehension trap for researchers working in colonial, early American, or English legal records.
Chronologically, the occupational meaning of "mystery" was already archaic by the mid-nineteenth century in common speech, though it persisted in legal instruments well into the nineteenth century through formulaic copying. A researcher dating a document partly from its language should note that the survival of this phrase in indentures reflects conservative legal drafting, not necessarily early origin.
The term connects directly to the law of apprenticeship, master-servant relations, and guild regulation. In the American context, cases such as those cited in Black's 2nd Edition — State v. Bishop and Barger v. Caldwell — arose from disputes about the scope of a master's teaching obligation, making the precise meaning of "mystery" in the indenture formula legally operative, not merely ornamental.
No meaningful jurisdictional variation exists in the legal meaning itself; the term was uniform in its occupational sense across English common law jurisdictions. Variation arises instead in how extensively different colonies and states developed apprenticeship enforcement mechanisms.
Historical Dictionary Support
All four source dictionaries agree completely: mystery means a trade, art, or occupation. Black's 1st and 2nd Editions, Anderson's, and Burrill's are unanimous on this point with no divergence. Burrill traces the word through Law Latin misterium and Law French mestier, both denoting an art or business — useful context for understanding why the word appears so frequently in formally drafted instruments drawing on older legal Latin and French vocabulary.
What the historical dictionaries do not address is the word's disappearance from active legal usage. By the time these dictionaries were compiled, "mystery" in the occupational sense was largely a relic of apprenticeship formula, and none of the entries flag this trajectory. A researcher relying solely on these dictionary entries gains the correct definition but no warning that the word is effectively extinct outside historical documents.
Jurisdictional Note
The occupational meaning of "mystery" is consistent across English and American common law jurisdictions. Its practical legal significance is concentrated in jurisdictions with active apprenticeship systems — primarily colonial and early American contexts, and in English law through the guild period. Modern legal instruments do not use the term.