quran

فَإِنَّهَا لاَ تَعْمَى الاٌّبْصَـرُ وَلَـكِن تَعْمَى الْقُلُوبُ الَّتِى فِى الصُّدُورِ

(Verily, it is not the eyes that grow blind, but it is the hearts which are in the breasts that grow blind.) means, the blind person is not the one whose eyes cannot see, but rather the one who has no insight. Even if the physical eyes are sound, they still cannot learn the lesson.

Hajj : 46