When we were sinners, we lost our sight and could not see anything. Our blindness was due to our sinful nature. In chapter nine the man was born blind, signifying that blindness is in the nature of a person when he is born (we have many aspects of blindness in us and this is why we need to experience Christ as our light. We sinners were blind by nature because we were born that way. Have you ever realized that every sinner was born blind? Therefore, if we confess that we are sinful, we must also admit that we are blind.