The concept of Shabbos is far beyond our comprehension.  We will never understand the full measure of the kedusha of Shabbos.  Shabbos is much more than refraining from doing the 39 forbidden labors.  It is a time when Hashem’s glory is apparent on earth.  The kedusha of Shabbos permeates every action a Jew performs.  For example, the berachah of Borei peri hagafen, “Who creates the fruit of the vine,” which we say in Kiddush, hold a higher level of kedusha than when it is said during the week.  And so it is with everything we do on Shabbos.

The degree of kedusha that enters a person’s heart depends on his readiness to receive it.  As it says, “It is a sign between you and Me, to know that I am Hashem who makes you holy!” (Shemos 31:13).  Shabbos is the instrument with which Hashem infuses holiness into our hearts.

~ Kuntres Chidushei Torah as quoted by R’ Dovid Meisels