Jagadguru Adi Shankaracharya on who in this world is really blind, deaf and dumb:
कोऽन्धः? – योऽकार्यरतः
को बधिरो? – यो हितानि न शृणोति ।
को मूकः? - यः काले प्रियाणि वक्तुं न जानाति ॥
Who is blind? He who knowingly keeps engaging in wrong acts.
Who is deaf? He who does not listen to right advice.
Who is dumb? He who does not know how to speak sweetly when the time arises or he who keeps quiet even when he knows someone is in danger.