By John Ostapkovich

PHILADELPHIA (CBS) — Yom Kippur, the holiest day of the Jewish calendar, begins tonight at sundown.

The tenth day of the year 5773, this Yom Kippur (the “Day of Atonement”) proceeds like it has for millenia — with fasting and prayer in temple.

Rabbi Lance Sussman of reform Congregation Keneseth Israel, in Elkins Park and Blue Bell, says the fasting during this observance is mandated for all but the young, the ill, and the pregnant.

(Rabbi Lance Sussman, holding a shofar. File photo provided)

Sussman (right) says the essence of the day is to set right one’s relationship with God.

“This is the day when we attend to our souls, that they should be good souls and that our behavior should then follow the purified state of our souls, then we should be the best people we can,” he says.

And Rabbi Sussman says fasting both cleans a person out from the inside and opens a window to the suffering of those in need, to spark compassion year-round.