Fifty-two years as a nominal Jew and I just found out about shatnez--sometimes spelled shatnes, sometimes shaatnez. I was walking down Coney Island Avenue, in the Midwood section of Brooklyn, home to many orthodox Jews, and I saw the sign in a tailor's window: "Have your garments shatnes checked." Shatnes, I wondered, what's that? Clearly it had something to do with some obscure Jewish practice or law. Tefillin checking I knew about. Tefillin, or phylacteries (which always makes me think of prophylactics) are leather boxes containing miniature scrolls with texts from the Torah, accompanied by leather bands for attaching them to your arms and forehead. Once, on the Lower East Side, I saw a sign in a Judaica shop window: "Tefillin Checking While U Wait." Tefillin have to be checked to make sure that the scrolls are in good shape, no rips or holes, etc., and that none of the lettering is obliterated. But what was shatnes checking?
I looked shatnes/shatnez up and learned that it refers to a prohibited mix of linen and wool in clothing. So it's sort of like kosher for garments. A suit with a wool and linen blend, to the ultra-observant, may well be as anathema as a cheeseburger. A few years ago the Times
did a profile of a shatnes tester
who refuses to eat in restaurants.
There are two biblical passages that specifically reference shatnez:
"You shall not let your cattle mate with a different kind; you shall not sow your field with two kinds of seed; you shall not put on cloth from a mixture of shatnez (Leviticus 19:19)."
"You shall not sow your vineyard with a second kind of seed. . . You shall not plow with an ox and an ass together. You shall not wear shatnez--wool and linen together (Deuteronomy 22:9-11)."
As with many ridiculous religious customs, there are multiple explanations for where the rule came from. According to Wikipedia, "Early writers, like Maimonides, argued that the prohibition was a case of the general law (Leviticus 20:23) against imitating Canaanite customs. Maimonides wrote that: 'the heathen priests adorned themselves with garments containing vegetable and animal materials, while they held in their hand a seal of mineral. This you will find written in their books.'"
"Where's your Moses now?"
But why settle for dissing those relatively modern heathen priests when there are those who'll put the blame squarely on old Cain and Abel? A difference of opinion about what kind of offering to make to the Alleged Deity (a sheep for Cain and some flax for Abel) led to calamity. In his usual inscrutable and capricious manner, the A.D. of the O.T. accepted Abel's offering, but not Cain's, so Cain, jealous and enraged, killed his brother. So heaven forbid you should have a little linen in your wool suit.
Some commentators say that shatnez is a hok, i.e., a law without any logical explanation which nonetheless must be obeyed. Yes, Kafka was Jewish. Could that tailor on Coney Island Avenue be running a hok shop?
You could also go with this positively new-agey explanation from the 13th century. According to the official website of The Shatnez Testers of America
Rabbi Aaron Halevi of Barcelona wrote in his book "Sefer HaChinuch - The Book of Mitzvah Education" the reason why it is forbidden to mix wool and linen together is because it destroys the spiritual fabric of the universe. This can be explained as follows: Each and every thing on earth, except for man, has its own spiritual force that influences it. When some of these earthly items are mixed together, they cause their spiritual counterparts to become entangled. Once entangled, they cannot perform their tasks as originally designed, thusly destroying the spiritual fabric of the universe. However, after the explanation, the author tacked on "We still need a Mystic to explain this." (Sefer HaChinuch - The Book of Mitzvah Education #62)
If you're concerned that you might be the victim of shatnez, this resource may come in handy.