This is based on the concept of eating and drinking the same food and drink as offered to the deity, as well as the belief that getting drunk to achieve an extraordinary state deepens exchanges with the deity.
他の神饌と同様の神と同じものを飲食するという意味のほか、酒に酔うことで非日常の境地に至り、神との交流を深めるという意味もある。