《礼记·郊特牲》
上天垂示日月星辰等等法象，圣人一一效法，郊天之礼就是为了让人们都知道效法天道的。
天垂象，圣人则之。郊所以明天道也。
Heaven manifests all kinds of phenomena, such as the sun, moon, and stars, and the sage imitates them one by one. The Suburban Sacrifice is meant to show the people the way to imitate Heaven.