日本傳教大師在唐時，道邃和尚傳授觀心之口訣，有此語。謂為一言之一心三觀。天真者謂本體不生也。吾人之一心一念，尋其本來不生而無相也。獨朗者吾人悟入此天真則本來無生死涅槃之別，宇宙朗然而光明，凡身即大覺之佛也。
The fundamental reality or bhūtatathatā, is the only illumination. It is a dictum of 道邃 Daosui of the Tang to the famous Japanese monk 傳教 Dengyō. The apprehension of this fundamental reality makes all things clear, including the universality of Buddha- hood. It also interprets the phrase 一心三觀 that 空中假 the void, the 'mean ', the seeming, are all aspects of the one mind.
一天真獨朗 謂了悟不生無作之本體，超越生死差別而朗然大覺。天台宗甚為重視，指為止觀圓滿之語，唐代道邃和尚傳授日僧最澄觀心口訣時用之。禪宗亦使用此語。摩訶止觀卷一（大四六‧一上）：「法門浩妙，為天真獨朗，為從藍而青。」〔止觀輔行傳弘決卷一、顯戒論卷一〕p1765