At the Pesach Seder the Urchatz is the washing of hands without a bracha. At the Pesach seder our table is like the altar, so since the Kohanim should wash their hands and feet in order to serve or make offerings, is the Urchatz symbolically referring to this washing? Or does it refers to another temple ritual? I wonder how it was established and by which basis we keep the urchatz ritual at the Pesach meal. Why don't we do Urchatz at for example the weekly Shabbat meal?