Yom Kippur is the only day in the year when each soul on earth comes closest to feeling its source.  The innermost dimension of the soul is revealed and shines forth only on this day.  This dimension of the soul — yechidah (“oneness”) — represents the inner unity of our souls, transcending all fragmentation, compartmentalization, all our dualities and pluralities.  It emerges only on Yom Kippur, “the Day of Oneness,” which falls on the 10th of Tishrei.

Ten is considered a complete number, encompassing all of existence and the entire cycle of time and space.  It is signified in the Hebrew alphabet by the letter yud, the first letter of the essential four-letter Name of G-d, the Tetragrammaton, which we are forbidden to pronounce.  Yud is written as a dot — the unifying point that fuses everything into the sacred oneness of G-d.

Sacredness/holiness, therefore, is the theme of this day, on which we try to be like angels.  As the 16th century scholar, the Maharal of Prague, put it, “All of the mitzvot that G-d commanded us on [Yom Kippur] are designed to remove, as much as possible, a person's relationship to physicality, until he is completely like an angel.”

On this day, we immerse ourselves entirely into the world of the sublime, minimizing in every way our interaction with the material, pluralistic, and fragmented world.  We consume no food or drink or engage in marital relations.   We do not bathe or anoint ourselves with creams or perfumes, and we do not wear leather shoes, which symbolize luxury.  We wear white and spend almost the entire day in the cocoon of the synagogue immersed in prayer.

We invest all our energy in this day, because on Yom Kippur anything is possible.  This we know from the very first Yom Kippur, the day which gave birth to hope.  If ever there was a day to begin anew, it is on Yom Kippur.  This is the day when we have the power to ask for anything we want — to achieve our deepest goals and dreams.  Yom Kippur is the single most important day in our lives.

So, make sure that you use this most special of days to the fullest.  But if for some reason you cannot, at least participate in the opening prayer, Kol Nidrei, and in the closing prayer, the Neilah.  (And if you have lost a parent, be sure to also participate in Yizkor, the memorial prayer.)