Three things then being asked,—if he were their son, if he had been blind and how he saw,—they acknowledge two of them: His parents answered them and said, We know that this is our son, and that he was born blind. But the third they refuse to speak to: But by what means he now seeth, we know not. The enquiry in this way ends in confirming the truth of the miracle, by making it rest upon the incontrovertible evidence of the confession of the healed person himself; He is of age, they say, ask him; he can speak for himself.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. lviii. 2