Ní bhíonn saoi gan locht.
There is no wise man without fault.
Note: A comparable English proverb is “Homer sometimes nods.” Perhaps Pliny said it best, “No man is wise at all times.” Pliny deliberately uses the word “man” to talk about wisdom. Like most ancient Romans, he thought wisdom was an exclusive attribute of men. In contrast, the Irish word “saoi” used to mean one who was the head of a monastic order. For Roman Catholics, that position could only be held by a man. However, for earlier druids, the word could be used to refer to a male or a female who attained such a position reserved for those of great wisdom.
Note also: The habitual present form of the verb “to be” is used, namely “bíonn.” This tense is used to describe situations that are usually the case. So the nuance of the verb for this proverb is that it is usually the case that there is no wise person without fault. (This truth is at the heart of the attack campaign which has become such an integral part of American politics.) A negative particle demands the following verb be lenited, hence the form, “Ní bhíonn…