The great medieval Jewish scholar, Maimonides, wrote that ancient pagan priests used to wear wool and linen together while practicing the occult and idol worship. Therefore, he reasoned, we should stay away from sha'atnez. In contrast, a more recent, non-Jewish writer said the reason for this law was that both the priestly garments of the Old Testament and the Tabernacle weavings were a combination of wool and linen, so laypersons were prohibited from dressing the same way.
Both comments could be legitimate, but the second has a problem. That the priest's white undergarment was made of linen and his vestment was made of wool is true, but they are two different articles of clothing, not one item of mixed fabrics. Deuteronomy 22:11 reads, “You shall not wear a [singular] garment of . . . wool and linen mixed together” (emphasis ours).
Another option offered by some is that mixing wool and linen upsets the environmental and/or metaphysical fabric of the universe. The Jamison, Faucett and Brown Bible Commentary asserts that
the observations and researches of modern science have proved that wool, when combined with linen, increases its power of passing off electricity from the body. In hot climates, it brings on malignant fevers and exhausts the strength; and when passing off from the body, it meets with the heated air, inflames and excoriates like a blister.
This was written in 1871, so when the authors refer to “researches of modern science,” they are speaking of not-so-modern research. Lest we make light of the seeming absurdity of this statement, other sources support this view. Articles, easily found on the Internet, tout the healing properties of linen and, to a lesser extent, wool, not to mention scientific studies that have measured the respective electronic frequencies of the human body and different fabrics. The most beneficial was linen, while silk had none at all. Wool did well, but its benefits were not nearly as good as linen.
Another possibility for God giving this command involves the story of Cain and Abel in Genesis 4. According to Jewish tradition, for what it is worth, the offering they were to give was for Passover. These same traditions have Cain bringing flax (from which linen is made) and Abel, a sheep (and thus wool). After Cain killed Abel, it was decreed, the thinking goes, that never again should the two substances mix.
Moreover, Abel's lamb resembles the paschal lamb, but Cain's offering recalls Egypt, which is identified by its production and use of linen. One rabbi went so far as to write that linen is unrighteousness and wool is righteous. He clarifies that wearing linen by itself is not forbidden, just that it represents Egypt. Yet, Revelation 19:8 tells us that the resurrected saints will be clothed in fine linen, clean and white, which would seem to demolish the “linen equals Egypt” theory.
A “Christian” website reasoned along similar but exactly opposite lines when it opined that wool is Old Covenant or “works,” and linen is New Covenant and “grace.” It went on to state that the two can nevermix!
Another explanation is that Leviticus 19:19 and Deuteronomy 22:11 are a kind of “consumer protection law.” Clothing is made from two basic kinds of natural fibers. One kind is from plant cellulose fiber, such as linen and cotton. The other is from animal protein fiber, such as wool and silk. Since they differ markedly in strength, washability, absorption, and so forth, they should not be mixed. Combining wool and linen produces a cheaper garment.
What we generally know about clothing agrees with this. A 100% wool suit is of higher quality than one of mixed types. A 100% silk tie is preferred over a blend, and so on. Wearing such materials in not a sin in itself, the argument goes, but instead, God does not want manufacturers producing shoddy materials in order to take advantage of their customers. A wise principle to follow in selecting either a pure or mixed garment is to purchase the best quality one can afford—it will last longer and fit better than inferior, less expensive clothes.
Wool and Linen