One more vort, be"H:
Malchus is the ends or tips of appendages. The tips of the fingers are
malchus of what each of the arms represent. Malchus is where the action is - it is the middah that is most kolel them all because it is where it all finally gets demonstrated. The
tachlis of anything is:
what it does or produces. Everything that symbolizes final purpose, is identified with malchus.
So, Shabbos is the tachlis of the week, and is therefore called malchus (Shabbos malkah); the days of moshiach are the tachlis of olam hazeh, and are about one basic thing: malchus Shomayim (v'hoyoh Hashem l'melech al kol ha'aretz, etc.); and the totality of the avodah of a person - his tachlis - is called his malchus ("ein malchus achas noga'as b'chavertah" is really the same as "ein odom nogeyah b'muchan lachaveiro," because a person's avodah/malchus is all about how he uses all his possessions and gifts from Hashem).
Now, the tachlis of any specific body part is symbolic of it's 'business end'. And the hand is the symbol of what the arm accomplishes. So the expression 'yad Hashem' just refers to Hashem taking
action, so we (and the nevi'im) call it His 'hand'. So the end of a thing - the last part, the part that does the final action - is it's malchus. Interestingly, the left side of a word is the
end of it in Lashon Kodesh, left being generally feminine (Din/Gevurah) and also more naturally associated with the midah of malchus.
[Interestingly, the roles of the genders are also related to all this in reproduction, where the man's contribution is only about giving, is short-lived, and only at the beginning (the right side of words in Hebrew - right being Chessed/male) - and the woman's role is the 'rest of the word' all the way to the end of it on the left side, is not about giving anything to anyone outside herself, but about forming and defining (Din/Gevurah) what she has been given. She protects the child in her confined womb...till at the end when the marriage's malchus ('bosor echod') is reached, symbolized by their child. She is much more closely associated with producing the child and so related to malchus all the more.]
OK, so now the vort:
The halocha is that if we scratch the scalp or any normally covered part of the body during learning Torah, we need to stop learning and wash (or clean them some other way). Same if mud gets on them - gotta stop learning and wash.
But if we are learning Torah and scratch our scalp with our forearm, or if mud gets splattered on our backs, arms, or heads,
we are permitted to go right on learning!
Why the hakpodah on the hands but no other part of the body?
Perhaps because hands are naturally symbolic of
ma'aseh, clean hands symbolize hands that are muchshar - ready -
to do. Muchshar to be 'klei ma'aseh' (malchus). But hands that are dirty have a p'gam. They may be able to do things, yes - but are symbolic of being 'improper' hands - unready to do.
If Torah-learning could be purely theoretical and not attached to ma'aseh at all - then there is no need to be shomer the hands. But Torah-learning that is theoretical and not attached to ma'aseh
is posul. The hands must be cleaned before learning is resumed, so that learning is only done with hands that are muchshar for ma'aseh.
Learning Torah Lishmah has been defined as learning for the sake of keeping it - of putting it into action (ShLo"H). Some sforim say 'Lishmoh' means 'Leshem Heh' - the letter 'Heh'...which is the last letter (way on the left side) of the Shem Yud-Keh-Vov-Keh. That letter symbolizes malchus, and final tachlis of His plan.
OK, so this vort is really a continuation of the vort before about Avrohom and the Akeidah. So is that cheating?