Fences

Rabbi Akiva Eiger in Teshuva siman 9 has a back and forth if one who buys a house and it has a mezuzah set up, does one say a beracha on the mezuzah since it is a new mitzvah for the new occupant.  Rav Scheinberg in Mishmeres Chayim asks why no one raises such a possibility regarding the mitzvah of having a fence around a roof, no one suggests that when moving into the house one should say a new beracha on the maakeh?  He answers that when it comes to mezuzah R.A.E. entertains the possability that a new house for this owner is a new mitzvah, there is a new מחייב,  and requires its own beracha.  However, the point of the maakeh, the fence, is merely to avoid danger and since there is no new danger, there is no new מחייב.

Tosfos Chullin (105a) says there is no beracha on removing danger.  So why is there a beracha on putting up a fence at all?  The Chazon Eish says that the bar of danger is not met by the place where one has to put op a maakeh and the mitzvah is to put up a fence despite not meeting the bar to be considered dangerous (discussed in greater detail in the post Put Up A Fence.)  (See also Likutay Sichos volume 2)  .In light of this, the answer of Rav Scheinberg becomes difficult for the מחייב of the fence is an independent mitzvah not due to sakanah?  

Rashi says כִּי תִבְנֶה בַּיִת חָדָשׁ: אִם קִיַּמְתָּ מִצְוַת שִׁלּוּחַ הַקֵּן, סוֹפְךָ לִבְנוֹת בַּיִת חָדָשׁ, וּתְקַיֵּם מִצְוַת מַעֲקֶה, שֶׁמִּצְוָה גּוֹרֶרֶת מִצְוָה, וְתַגִּיעַ לְכֶרֶם וְשָׂדֶה וְלִבְגָדִים נָאִים, לְכָךְ נִסְמְכוּ פָּרָשִׁיּוֹת הַלָּלוּ.  Normally מִּצְוָה גּוֹרֶרֶת מִצְוָה means that one mitzva leads to another but here it is leading to a new house which happens to have a mitzvah etc., how is that מִּצְוָה גּוֹרֶרֶת מִצְוָה?  We see that it doesn't merely mean one mitzvah leads to another but that when one does a mitzvah one's outlook in life becomes different.  When one does a mitzvah he starts viewing additional things as mitzvah opportunities.  When the person gets a new house he sees the mitzva of maakah, the fields, the mitzvot associated with the fields etc.  The mitzvah allows him to see additional mitzvot in other areas (see also Divrei Chaim l'maancha Elokim chaim.)

The Rebbe (Likutay Sichos volume 2) says the message of saying a beracha on making the roof is that when one builds a new house, meaning when one reaches a new form of avodah, in order to avoid stumbling one must build a roof which is raised above the house.  One must bring down a greater level to watch and protect over the person.  How is that possible?  By making a beracha, by connecting and bringing into the world the Divine assistance which will allow for one to tap into a level above their own in order to be successful in their new endeavor.