The Princess and the Shaatnez

There is an account in gemara Beitza, coming up in daf Yomi, on Beitza 14b, about the Holy Congregation of Yerushalayim.

From a Biblical perspective, shaatnez is only a problem to wear. Sleeping directly on shaatnez, with the shaatnez under you, is no problem. This is because, as the brayta says, the pasuk in Vayikra 19:19 states:

יט אֶת-חֻקֹּתַי, תִּשְׁמֹרוּ--בְּהֶמְתְּךָ לֹא-תַרְבִּיעַ כִּלְאַיִם, שָׂדְךָ לֹא-תִזְרַע כִּלְאָיִם; וּבֶגֶד כִּלְאַיִם שַׁעַטְנֵז, לֹא יַעֲלֶה עָלֶיךָ.

19 Ye shall keep My statutes. Thou shalt not let thy cattle gender with a diverse kind; thou shalt not sow thy field with two kinds of seed; neither shall there come upon thee a garment of two kinds of stuff mingled together.

with a midrashic emphasis on the words yaaleh alecha. They should not come upon you. yaaleh implies over you. But under you would theoretically be permissible. Yet the Sages imposed a decree lest a single thick thread of shaatnez under you come upon one's flesh, and thus be over it, which would be a violation of Biblical law.

As the gemara notes, the Holy Congregation of Yerushalayim said that even ten bedspreads, one upon the other, and shaatnez underneath them, it is forbidden to sleep upon them.

This is somewhat reminiscent of the popular fairy tale of the Princess and the Pea, who showed how refined she was (as opposed to how holy she was) by not being able to sleep over many mattresses, underneath which was a single pea.

Just thought it was an interesting comparison.