"You shall not sow your field with a mixture of seeds, and a garment which has a mixture of Shatnez shall not come upon you."¹

"You shall not wear a mixture of wool and linen together."²

B. Shatnez (pronounced SHOT-nezz) means "mixture." Shatnez is a spiritually unhealthy mix of materials. In Negative Mitzvah #42, wool and linen materials may not be spun, woven, sewn or worn together. Shatnez only applies to a mixture of wool and linen. Any other materials may be combined, such as silk and cotton.

C. Shatnez is a Chok -- a mitzvah whose complete reason will always elude human intellect. However, several partial reasons have been suggested: 1) Shatnez was worn as a sort of uniform by clergy of idolatrous religions; 2) the Kohanim wore shatnez uniforms, therefore, we may not; and 3) Flax (linen) was Cain's sacrifice, while sheep (wool) was Abel's, and bringing the two together brought about negative consequences.

How do I check for shatnez?

1. Episode I--On the Trail

You are an undercover shatnez detective, sneaking about Macy's. Wool/linen combos are your targets. 100% cotton shirts/socks/underwear? Harmless bystanders. Silk ties? OK. Polyester/rayon/nylon sportswear? Dead-end lead. Denim? Distraction. "One hundred percent" wool suits or slacks? Buy 'em. Proceed with extreme caution. Call for back-up. Dangerous suspects.

2. Episode II--Investigating the Evidence

You pay at Checkout and secure an item return slip--just in case. You head out the door with the woolen suspects, acting calm. Your back-up is waiting. You head to your rendezvous at the Shatnez Lab.

3. Episode III--The Verdict

The expert at the Lab hunches over his workbench, inspecting the suspects intensely. He surgically removes a pinch of threads from their inside linings for analysis. "It mostly depends on where they're made," he tells you without looking up. "Companies constantly switch factories all over the world--so you always gotta check stuff out. Also, which companies--some cheat by mixing linen into their wool, and some are more honest." "Great, Dr. Rabbi," you grouch from under your rakishly-angled-standard-issue-undercover-detective hat, "but what about my Armani? What about my pants?" "Well..." he pauses, painfully increasing the suspense, "...they're good." You breathe deeply. "But it's a good thing you brought 'em in. You never know." You sweep out the door, trenchcoat billowing behind you, new clothing in hand. Case closed.