Focusing on the kedusha of Tefillin.  While wearing Tefillin, one is required to remain cognizant of this fact and behave in an appropriate manner.  This Halacha is derived from the pesukim discussing the Tzitz in Parshas Tetzaveh.  We discuss the essence of the term Hesech Hadaas (is it just an awareness or a real conscious thought) and how this definition translates into Halacha L'maaseh.  For example, what should one be concentrating on when reciting the Shema while wearing Tefillin - on the Tefillin or on the words of the Shema.  Also, if one does in fact lose focus of the fact that he is wearing his Tefillin, was he still mekayem the Mitzvah of Tefillin?