Nullius nisi?

[Ciaciaufufu]

Regarding the sentence: cuiusvis hominis est errare nullius nisi insipientis in errore perseverare.
I have understood as a whole the meaning to be "every one makes mistakes but only a fool would persist in error", but I can't wrap my mind around the latter clause's grammar.

Cuiusvis hominis = dative
errare = subject
est = verb
Now that was clear for me but I don't know how "nullius nisi" resolves to "only".

Thank you.

 

[Pacifica]

Cuiusvis hominis = dative

No, genitive.

This is how it works, literally:

It is [the characteristic] of any man to err, [but it is the characteristic] of none but (= nullius nisi) a fool to persist in error.

 

[Ciaciaufufu]

No, genitive.

This is how it works, literally:

It is [the characteristic] of any man to err, [but it is the characteristic] of none but (= nullius nisi) a fool to persist in error.

OMG it was so obvious it was a genitive I am so ashamed of myself.
That was crystal clear thanks.