This sugya explores a fascinating Machlokes amongst the Poskim regarding the Kedusha of objects that are used in the performance of a mitzvah. These objects - Sifrei Torah, Tefilin, Tashmishe Mitzvah, Shaimos, etc. - have differing levels of Kedusha and must be handled accordingly. In addition, one must be careful not to downgrade an object from a higher level of Kedusha to a lower level. For example, since Tefilin Shel Rosh is holier than Tefilin Shel Yad, one may not use the straps from the Shel Rosh for the Shel Yad, as it is considered defiling the original Kedusha.
An even more intriguing debate discusses whether different levels of Kedusha can be found within the same single item. Are all parts of the item equal in Kedusha, with no regard as to each part's proximity to the point of Kedusha? Or, is the part of the item closest to the Kedusha considered to be the holiest? This can apply to Tefillin straps, the top of the Talis vs bottom, the front of Tzitzis vs back, and possibly even Sukkah boards.
This Machlokes HaPoskim is based upon how we understand the well-known Chazal in Parshas Vayeitzei. This Chazal describes the miracle in which the many stones under Yaakov's head were converted into one, thereby appeasing all the stones by having Yaakov rest on them, even though his head was still resting only on one part of the unified object.