Chinese idiom · 成语
一念之差
Meaning
A moment’s errant thought; a slight misjudgment.
Character by character
Origin and story
literary allusionSong poetry provides both an antecedent and the exact expression. Su Shi playfully imagines an error of thought in an earlier existence, perhaps connected with a previous life as a master of cursive calligraphy. Lu You's poem at Zhangren Temple uses the full phrase to contrast familiarity with a sacred text and entanglement in worldly affairs. These are poetic reflections drawing on religious ideas, not independently verifiable reincarnation stories. The expression later broadened to a momentary lapse of judgment with consequences beyond the moment itself. The 'smallness' belongs to the initial thought, not necessarily to the resulting harm.
Sources and further reading
In everyday life
他一念之差，在报名表上填了假成绩，最后失去了参赛资格。
In a moment of poor judgment, he entered false results on the application and ultimately lost his eligibility to compete.
Usually concerns an impulsive or mistaken choice, often with serious consequences.