When Rabbi Yochanan ben Zakkai lay dying, his disciples came to gather at his bedside. They expected composure from the man they called the Light of Israel, the Pillar of the Right, the Mighty Hammer. Instead, they found him weeping.
Astonished, they asked, "Light of Israel, why do you weep?"
The old master answered them with the clarity of a teacher whose final lesson would outlast his breath. "If I were being led today before a king of flesh and blood," he said, "a king who is here today and tomorrow in the grave, whose anger cannot last forever, whose death sentence cannot endure forever, and whom I might yet pacify with words or bribe with silver, even then I would weep. How much more now, when I am about to stand before the King of kings, the Holy One, blessed be He, whose anger is everlasting, whose sentence admits no reprieve, who cannot be softened by argument or silver. Two roads stretch before me, one to the Garden and one to Gehinnom, and I do not know which I will walk. Shall I not weep?"
His students bent close and begged, "Rabbi, give us your blessing."
He gave them one sentence, and it is worth a library. "May the fear of Heaven be upon you as much as the fear of flesh and blood." He meant: you already know how to behave when a neighbor might see you. Learn to behave the same way when only God is watching.