智者千虑，必有一失 - Chinese Idiom

智者千虑，必有一失:

Literally means:

a wise man, even with one thousand ideas, may make a mistake; even the wise are not free from error

Actually means:

智者, an intelligent person. 千, one thousand, but here it is a functional word, indicating a large number consider.

This phrase means a wise man, even though he considers all possibilities, can not avoid slips.

It is usually used to console some one who has made an accidental mistake, or to show understanding of him. It is also used to warn people not to be so self-confident as to believe that he may make no errors.

智者，聪明的人。千，是一个虚数，这里表示次数很多。虑，考虑。

智者千虑，必有一失，聪明的人考虑事情虽然很周到，但是也有失误的时候。

用来对偶然失误的人表示安慰或谅解，也用来提醒人们，不要自以为聪明，做事没有任何漏洞。