A Good Example:

Imagine yourself in a dark room/space. Your eyes are wide-opened due to excessive use of caffeine or maybe even because someone or something is holding it open so hard and so tight that you can’t close it even if you wanted to — Note, the latter is the worst case scenery — you’d have no other choice but to experience a series of negative emotions, which could be anger, fear, weakness etc. But, what happens when a large beam of light suddenly shines through your forcefully opened eye? You shut it at all cost. Why is that?