When your eyes are functioning well you don't see your eyes. If your eyes are imperfect you see spots in front of them. That means there are some lesions in the retina or wherever, and because your eyes aren't working properly, you feel them. In the same way, you don't hear your ears. If you have a ringing in your ears it means there's something wrong with your ears. Therefore, if you do feel yourself, there must be something wrong with you. Whatever you have, the sensation of I is like spots in front of your eyes - it means something's wrong with your functioning.