Tashlich — which means "to cast" or "to throw" — is a quaint ceremony that comes to us from the Middle Ages, but it so captures the human condition and the human spirit that it should be part of every Jew's Rosh HaShanah observance.

The premise is quite simple: into a body of flowing water — a river, a lake, a stream, an ocean — we symbolically "cast our sins and transgressions." With a number of short, poignant, and deeply personal prayers, we throw bread crumbs or pocket dust or pebbles, representing our sins, into the water, to be carried away by the gentle flow.

Wayne Dosick, Soul Judaism