That explains Measure for Measure 4.2, where Pompey asks Abhorson the executioner why he considers his trade a 'mystery'. Does he quibble on the two meanings, or is he just arguing whether it takes any particular skill to do the job? Hard to say without further study.

Surely the meanings overlap in many cases: an expert's skill will not only involve mastering the subject, making it a mystery in the sense of this post, but will often be a mystery in the usual sense to outsiders who do not understand how he does whatever he does.

Exactly, and well put.

A word familiar to Eng. Lit students and mediaevalists from the collocation 'mystery plays', performed by the guilds. My wife was in once. She played Envy, and allegedly did a pretty decent Middle English.

Ah, but that is the first mystery, the familiar one with the straightforward etymology. The collocation is based on the OED's sense 4:

"Christian Church. An incident in the life of Christ or (occas.) a saint, regarded as a subject for contemplation or as having mystical significance. Also spec. (chiefly R.C. Church): each of the events relating to the life of Christ commemorated in the rosary; (hence) each of the divisions of the rosary commemorating these events."

Hmm, I'm sure I learnt different, and I had thought from the OED itself. I wonder what the authority for their derivation is. In fact, I remember there being some debate on this somewhere, but I was under the impression they had come down in favour of n. 2.

Skeat likes mistery play, for what it's worth.

I am puzzled why anyone would prefer "occupation" over "religious rite" as a base sense for "mystery play."

I think that the original meaning is not so much "occupation" but "secret", applied to crafts and techniques, so the order of presentation is indeed puzzling.

"Mystery play" (= Old French "mistere") refers to the theatrical representation of religious episodes or allegories.

I think that in the medieval age what we think of as ordinary things tended to be mystified and sacralized in a way we might find ridiculous, partly just to keep trade secrets secret. A very strong case is metallurgy, which was associated with alchemy and was also a secret craft.

There were a lot of terms associating litercy, math, algebra, Latin, etc with magic or the mysterious: gramery, latis (for latin, the unintelligible language of birds), abracadabra (from alphabet?), spells, runes, jargon, etc.

Don't forget masons/freemasons.

See also, at OED entry "degree n. ... II. Specific and technical senses":

7. A stage of proficiency in an art, craft, or course of study: a. esp. An academical rank or distinction conferred by a university or college as a mark of proficiency in scholarship; also (honorary degree) as a recognition of distinction, or a tribute of honour. Also in legal use.
...
[1284 Chart. Univ. Paris. I. i. No. 515 Determinatio [i.e. the Disputation for B.A.] est unus honorabilis gradus attingendi magisterium.]
...
a1794 Gibbon Autobiog. 29 The use of academical degrees, as old as the thirteenth century, is visibly borrowed from the mechanic corporations: in which an apprentice, after serving his time, obtains a testimonial of his skill, and a licence to practice his trade and mystery.
...

I love this use of the word. Shakespeare also employed this sense in Othello 4.2, when Othello yells at Emilia to mind her own business and leave him alone with Desdemona: "Cough, or cry “hem,” if anybody come: / Your mystery, your mystery; nay, dispatch."

He plays trippingly on the equivocation in Measure for Measure, Act 4 Scene 2:

ABHORSON. Do you call, sir?
PROVOST. Sirrah, here's a fellow will help you to-morrow in your execution. If you think it meet, compound with him by the year, and let him abide here with you; if not, use him for the present, and dismiss him. He cannot plead his estimation with you; he hath been a bawd.
ABHORSON. A bawd, sir? Fie upon him! He will discredit our mystery.
PROVOST. Go to, sir; you weigh equally; a feather will turn the scale. [Exit]
POMPEY. Pray, sir, by your good favour – for surely, sir, a good favour you have but that you have a hanging look – do you call, sir, your occupation a mystery?
ABHORSON. Ay, sir; a mystery.
POMPEY. Painting, sir, I have heard say, is a mystery; and your whores, sir, being members of my occupation, using painting, do prove my occupation a mystery; but what mystery there should be in hanging, if I should be hang'd, I cannot imagine.
ABHORSON. Sir, it is a mystery.
POMPEY. Proof?
ABHORSON. Every true man's apparel fits your thief: if it be too little for your thief, your true man thinks it big enough; if it be too big for your thief, your thief thinks it little enough; so every true man's apparel fits your thief.

Argh! I missed all that about Measure for Measure earlier. Sorry!

In Defoe's Robinson Crusoe we find just one use of mystery, and it is arguably poised between the "skill or trade" meaning and the "enigma" meaning. At least the passage shows how close the two senses can be. Crusoe initiates Friday into a skill, or unveils an enigma:

I let him into the mystery, for such it was to him, of gunpowder and bullet, and taught him how to shoot; I gave him a knife, which he was wonderfully delighted with, and I made him a belt, ...

We find the "skill or trade" meaning in Smith's Wealth of Nations:

By the 5th of Elizabeth, commonly called the Statute of Apprenticeship, it was enacted, that no person should for the future exercise any trade, craft, or mystery at that time exercised in England, unless he had previously served to it an apprenticeship of seven years at least; ...

"mystery" as opposed to "skill or trade" must refer to something more abstract than ordinary "trade" and "craft", perhaps what we would call "art" or "professional qualification".

Sure, Marie-Lucie. That's why I cited all that about magisterium, as "a stage of proficiency in an art, craft, or course of study", etc. (OED). Even classically it meant a high rank or degree.

Noetica, I was not disagreeing with you! but it seems that there was a lot of confusion earlier about mystery and mastery, probably in part because in Middle English the stress would have been on the last syllable as in French (eg misteRIE/masteRIE), something which causes unstressed syllables to end up with the same vowel sound in pronunciation.

When I used to see this word, I forget where, I just came to assume that "mysteries" meant craft secrets, trade secrets, and special methods, in a hierarchy ranging down from astrology and alchemy through medicine and metallurgy to things like weaving and leather working. In one sense it was a substitute for patent and copyright protection, and in another a way of building up the product's value in buyer's eyes.

In the middle ages there was a sacred-secular divide, but it was different and ours and lots of activities had their funky sorts of semi-orthodox sacredness, with guardian angels and patron saints and so on. I believe that guilds opened their meetings with special religious rituals. In overtly polytheistic societies this was much more pronounced. Our secularity is more secular than earlier secularity, which was firnly subordinated (ideologicaly) to the sacred, even if not really in fact.

This doesn't add anything to the question at hand as to the precedence of the two meanings, but does show that they're closer and easier to confuse than we'd first think.

Theorists would tell you nowadays, m.-l., that you can't use the word 'art' in this sort of context if you're talking about anything that was made before, roughly, Kant's Critique of Judgment. It may seem nit-picky, but it is relevant if we're talking about mystery and mastery.

AJP, I am not familiar with Kant or other theorists you may have read, but I agree with John Emerson's first paragraph just above. By "art" earlier centuries meant something much more comprehensive than what we understand now and that's what I was referring to. (In French l'homme de l'art is still a rather literary description for a medical doctor, never for an artist).

England has Sweeney Todd and the barber surgeons.

Ah! the mastery of the mystery.
Re: Knowledge was not for general consumption, for centuries 'twas so. [Failure of Eden I guess]
The Printing Press started the downward travel to get knowledge for the masses. It was why some religions spoke in foreign tongue to the "m-asses",Laws were not available in the local tongue.
Apprenticeships were needed, to provide goods,but skills were obtained but limited to few, so that knowledge would not available to the unprivileged, many secrets were lost because of the lack of documentation and keeping the mystery in ones head. [one such secret be staining of ancient glass windows, still be a mystery that needs mastering.
There are still many disciplines that fail to make known their mysterious knowledge, it being the prerogative of the those that mastered the specialty, many doctors of this and that hide behind the parchment of their apprenticeship,
But people are finding the tree of knowledge via the internet.

Thus demystifying the secrets of mastering wealth for the few, now more are able to master the controls of their fate.

Economics be still major subject that be mystifying the world that still requires some mastering .

Similarly: (government) policy vs (insurance) policy

Like Conrad, I learned that mystery plays were so called because they were sponsored and performed by guilds. See, for example, the York Plays in which each mystery is associated with a particular mystery.

I could see that argument if there were a clear textual tradition linking the term to that meaning and if the plays weren't all about Bible stories. Things being as they are, I think Occam's razor points to the obvious etymology.

As I mentioned earlier, the English mystery plays correspond to the Old French misteres, but that word never had the meaning "trade, craft, etc" which the English one seems to have had. Instead that meaning persisted in French métier which is from Latin ministerium (says the Petit Robert), apparently one of the sources of English mystery through confusion of the two Latin words. The English mystery plays may have been put on by guilds of craftsmen, but the mysteries represented were religious ones, just as in French in the same period.

Here's a data point from Chaucer:

"In youth he learned had a good mistere.
He was a well good wright, a carpentere."

613-14 in the General Prologue, describing the Reeve. Does the trade seem particularly sacred or secret here?

I am feeling a bit of ambivalence here.
On one hand, isn't the purpose of language to communicate comprehensibly? So "correct" usage is defined by what is commonly understood, and if people start confusing things, the confusion would seem to defeat the purpose of communicating.

On the other hand, language would be a lot less interesting without such delightful semantic ambiguity to play with. The example from Measure for Measure is excellent. Was Shakespeare intentionally playing on a double meaning there, or would he have had only one in mind? If the former, it's rather ingenious.

Of course Shakespeare was playing on the double meaning (as in many other cases), but we moderns only know the meaning "secret" or "unfathomable" and can't understand this particular exchange.

If you google "art or mystery" (or "and mystery" and try also the variant spelling "mistery") you will get lots of old legalese documents using the trade-or-skill sense. I have seen mid 20th century U.S. legal formbooks using it in boilerplate for an indenture of apprenticeship (the master undertaking to teach the apprentice the "art and mystery" of blacksmithing or whatnot) but I expect the form was archaic even then as the old style of apprenticeship had become generally obsolete. I had thought Dylan Thomas had also used it in this sense, but it seems I was misremembering the poem beginning "In my craft or sullen art."

When i took part in a UK gardening discussion group on the web, about ten years ago, I used the name 'Wysterious', but I was never sure that it oughtn't to have been 'Wisterious'.

Take a couple of days off and what happens? You guys get on a fascinating subject (actually several) without me knowing about it.

From the time of ancient Egypt the skills associated with trades were closely held secrets in order to protect the power of the associated guilds. A millenium long association of a titulary god or saint with the each trade (sometimes varying from one vicinity to another) testifies to the religious quality of those secrets. They were a sacred gift to their practioners by the god. Thus "mysteries," even as it relates to trades and duties is totally in accord with the religious meaning and only later (when trade secrets were secularized but ancient usage lingered on) did the term become carried over to duties and professions apart from gods.

Thus the "Masons," while they themseves no longer practiced the construction of the pyramids, split off and kept alive those mysteries of the builders which were extraneous to the actual trade but not to psychic life, and certain of the "metal workers," who no longer practiced metal working, kept alive those soul-deep mysteries of metal working which were extraneous to the practical trade as "alchemy".

There are vast amounts more to be said on the conversation above. Not all religious rites were "mysteries". Not by any stretch of the imagination. Until Christianity, rigorous and exclusionary preparatory rites requiring initiation, and invoking concomitant psychological frenzy (the payoff, as it were), in order to be introduced to the secrets of life were "mysteries." The omomphagia and taurophagia were "mysteries". The Eleusian mysteries were a way station between the mysteries of ancient vegetation gods and Christianity (thus the vast number of wheat symbols in Christianity).

Many are called but few are the thrysis bearers, Hat. There is vastly more to be said.

Make that "Thyrsus bearers".

As someone who has actually borne a thyrsus (see Addendum here), I feel I have a certain expertise here. You are talking about religion; I am talking about words. I have little interest in the history of trade secrets, but that's not what we're talking about in any case—we're talking about the English words mystery, one of which ('mystery') is from Latin mystērium and the other ('occupation') from ministerium. No amount of historico-religious exegesis will change the facts of English usage.

While I do not have an OED immediately at hand, my Oxford Dictionary of Etymology has it "by association with mysterium." The reference is somewhat vague, true, but clearly refers to the word being a catalyst ("minister" being a demotic pronunciation?) via "OF mistere". Webster's New International 1913 has it mysterium by way of OF mistier (F metier) which is a very common route for etymologies in the period in question.

I can not help but wonder aloud if maybe OF maistrie has even better demotic possibilites making the use of "mystery" a variant pronunciation of "mastery". The Oxford Etymological finds magister/minister confusions in the history of the words "master"/"mister" and includes the following exemplary entry:

"mister (obs. exc. arch. and dial.) handicraft, employment;... office, duty; need, necessity. XIII - AN mester, OF mestier...: Rom. misterium, for L. ministerium."

This "mister" is clearly the noun of your "mystery" but comes from roots, the reader is informed, that are understood to be derived not from minis-try but from magis-try. That until the final "L. ministerium" which it states (vide supra) is "by association with mysterium."

Add to this that "magus" is a word borrowed into the Greek language from the Persian mystery religions (hence "magis," "magic" etc.) where he or she was the adept. Maybe I will find the OED's derivation of mystery-2 so convincing (with overpowering mini-quotes, as it were) that I will feel this all was set aside by wiser heads and that ministerium and ministerium with no meaningful influence from either mysterium or magisterium is the source of the word.

Misread my ancient Greek etymological dictionary (Bailley/Chantraine Edition Francaise) and now have to retreat most shamefacedly from magnos/magos link. The latter only appears to be listed under the former due to a printer's error. The two, I assume, have no shared history. The rest of the previous post survives reflection.

I know you are just hanging on a thread to learn if I will be able to derive the IE relationship between "magnos/magos" and overcome the printer's error to which I've referred, and, at last, I can unretreat. Numerous IE databases, root dictionaries and commentaries confirm the the two are IE first cousins mag- (large) and meg- (powerful/great/outstanding, as a noun "powerful adept/priest") or even from the same root. Magnus did retain the secondary meaning of powerful/great in classical times (fr. Cassell's). Magisterium did refer to the elite of the Catholic priesthood in the Middle Ages (ministerium to all priests, admittedly) and was used thus in Livy and Suetonius on at least one occasion each (again Cassell's). Still, it is not possible, at present, to say how much (if at all) the magis- of magisterium was culturally mindful of its relationship to magus.

Magisterium did refer to the elite of the Catholic priesthood in the Middle Ages (ministerium to all priests, admittedly) and was used thus in Livy and Suetonius on at least one occasion each

What exactly were Livy and Suetonius referring to, hundreds of years before the Middle Ages?

The Catholic Church borrowed many of its terms, offices and structural components from the pagan religons that preceded it. Perhaps the most famous instance being the Pope's title of "Pontifex [Pontiff] Maximus".

The Roman Catholic church has many fine structural components to its own credit, thanks including several kinds of vaulting, the glass curtain wall and flying buttresses. They subsequently employed the greatest names in Italian and German Baroque architecture. Stonehenge is nothing compared to Guarini's spiral at the Cappella della S. Sindone, in Turin.

"A very strong case is metallurgy, which was associated with alchemy and was also a secret craft. "

Earlier than that metallurgy was simply considered a form of magic. Patrick (supposedly) specifically mentions smiths as one group he asks protection from, along with witches and druids, in the Lorica.

Isaac Newton spent years researching alchemy and metallurgy, longer that he spent on the other stuff. Unless we imagine we're smarter than him, I think we ought to use some humility when we ridicule the premise of alchemy by offering 300 years of scientific hindsight.