8th PRINCIPLE: The journey from the Written Tora to the halakhic practice

Last week we explained that the first category of laws of the Oral Tora is the PERUSH, that is the basic definition of each Biblical precepts and its extension (see this).
The second category is called Halakha leMoshi MiSinai. Briefly, this category also defines the details of the mitsvot, perhaps more specific details than the first category, such as: the color of Tefillin, the size of a mikveh, the amount of matsa  to be eaten on Pesah, etc. What is the difference between these two categories?
While for the category PERUSH there is always some biblical allusion or source, the specifications classified as Halakha is leMoshe miSinai do not have a Biblical source.
What do they have in common, these two categories? The details of the mitsvot included in both categories (1) were received by Moshe Rabbenu and (2) there is no disagreement on them.
Let’s clarify this last point: Many times there is no consensus among the rabbis about certain laws. This rabbinical dissent  is known as “mahloqet” (lit. debate, discussion, disagreement).
Let’s continue with the example of Tefilin:
The WRITTEN TORA says: “You shall bind them as a sign on your arm.” No further specification in the text about how to “binding words to the arm”.
The PERUSH, says: this is the arm’s Tefilin, which should have four biblical texts, inside a leather box, which should be placed in the weakest (usually the left) arm, etc.
HALAKHA LEMOSHE MISINAI: The box of Tefilin must be square, the leather straps: black, the knot should be done a certain way, etc.
On all these and many other details there is a complete consensus among the Rabbis. Which, according to Maimonides, “It is evidence that these details and explanations were received by Moses at Sinai.”
For Maimonides, every detail of the Oral Law upon which there is disagreement, was not received by Moses at Sinai.
This brings us to the third category. DINIM MUFLAIM These are the details of the laws, the largest of the five categories in terms of the items it covers, that although they define a biblical commandment, are not considered of biblical but rabbinical origin and status. As Maimonides says, they were not received “directly” by Moses at Sinai. Rather, they were defined by the rabbinical courts or by the rabbis of each generation.
A modern example of a “DIN MUFLA”
Can I put the Tefilin strips over my watch? Or should I remove my watch first and placed the leather straps directly on my skin?
The answer to this Halakhic question was not transmitted “directly” to Moshe at Sinai. But there is indeed an ancient Halakhic concept that encompasses this and other similar cases: to concept of “hatsitsa”, that is, when something interrupts between the body and the element with which we perform a mitsva.
There cannot be a hatsitsa, for example, when we wash our hands ritually, netilat yadayim. That is, I cannot have traces of clay, ceramic or any other physical element in my hands when I do netilat Yadayim. I must wash my hands first, remove the hatsitsa, and then proceed to do netilat yadayim. Something similar happens in the case of the mikve: a woman must wash her body first, and verify that no foreign element is on her skin when immersing in the mikve.
Now a watch, evidently, is a “hatsitsa”, an element that stands between the Tefilin and my skin. The question is whether the law of hatsitsa for Tefilin applies to the  arm, forearm and hand or applies only to the arm, where the straps are holding the actual Tefilin.
Rabbi Obadia Yosef explains that the prohibition of having hatsitsa in Tefilin is learn from a pasuq (על ידך). That is, this law is not Halakha leMoshe MiSinai  but rather  a law of the highest category, that is: PERUSH.
Then Rabbi Yosef brings a short discussion on the reach of hatsitsa. According to most Rabbinical opinions hatsitsa only applies where the Tefilin box is placed, in the arm, (מקום הקשירה). According to other opinions, it would also apply thru the forearm until the wrist. Rabbi Yosef concludes that technically hatsitsa law does not apply to the wrist, where the watch is worn, and therefore there is no problem in wearing the tefilin’s straps over the watch (but he also clarifies that conceptually, it is best to remove the watch when using the Tefilin, והמחמיר תבוא עליו ברכה).
We can see in this typical case how the different categories of laws included in the Oral Tora work in the development of an halakhic conclusion.
Rabbi Yosef Bittón
Ohel David UShlomo Congregation
710 Shore Blvd, Manhattan Beach
My dear friend, Dr Daniel Banilevy from Great Neck, N.Y., found and sent me a translation of the Mate Dan in English,”THE ROD of JUDGEMENT”, the first dialogue, by Dr Loewe, London, 1842.   Kindly uploaded by Google books.
Download here .
Thanks so much Dr Dani