even a wise man sometimes errs; Homer sometimes nods
A proverb meaning that even a person of great wisdom or careful thought can make a mistake. Often used to console someone after a rare error or to acknowledge one's own slip. The phrase comes from the Chinese classic 'Records of the Grand Historian' (Shiji).
Even an expert like him can make a mistake sometimes; it's a case of 'even Homer nods.'
千慮の一失で、大事な書類にミスをしてしまった。
Due to a rare slip, I made a mistake on an important document.