《资治通鉴·汉纪·汉纪七》
于是，决定把文帝在位的第十七年改称为元年，并特许天下人聚会痛饮，以示庆贺。
于是始更以十七年为元年，令天下大酺。
So it was decided that the 17th year of Emperor Wen's reign would be changed to the first year, and the people of the world were permitted to gather and have a good time to celebrate.