In addition to His eternal spiritual commandments, God gave Israel various statutes and judgments as part of its civil code or national law. Most aren't binding laws for Christians today, but Christians should consider and learn from the principles contained in all of them. Is there any principle in these laws or in their intended purpose that can guide Christians in everyday life?
In its introductory notes on Leviticus, Expositor's Bible Dictionary points out:
"The weaving of two kinds of material (wool and linen in Deuteronomy 22:11 Deuteronomy 22:11You shall not wear a garment of divers sorts, as of woolen and linen together.There is no apparent application today for two reasons: (1) Most Christians do not make their own fabric or clothing today, and (2) clothing manufacturers do not mix these materials.
American King James Version×) may be a rule that would prevent loss by unequal shrinkage."
However, the broader principle of the several statutes that forbid "mixing" in various ways is that God wanted His people to pursue purity and quality. Similarly, Christians are to pursue pure and godly character. The Jamieson, Fausset and Brown Commentary offers the following explanation for Leviticus 19:19 Leviticus 19:19You shall keep my statutes. You shall not let your cattle engender with a diverse kind: you shall not sow your field with mingled seed: neither shall a garment mingled of linen and woolen come on you.
American King James Version×:
"Neither shall a garment mingled of linen and woollen come upon thee—Although this precept, like the other two with which it is associated, was in all probability designed to root out some superstition, it seems to have had a farther meaning. The law, it is to be observed, did not prohibit the Israelites wearing many different kinds of cloths together, but only the two specified; and the observations and researches of modern science have proved that 'wool, when combined with linen, increases its power of passing off the 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' [Whitlaw]. (See Ezekiel 44:17-18 Ezekiel 44:17-18  And it shall come to pass, that when they enter in at the gates of the inner court, they shall be clothed with linen garments; and no wool shall come on them, whiles they minister in the gates of the inner court, and within.
 They shall have linen bonnets on their heads, and shall have linen breeches on their loins; they shall not gird themselves with any thing that causes sweat.
American King James Version×.)"