/ http://www.slideshare.net/images/logo.gif / 際際滷Share feed for 際際滷shows by User: bijeugm https://cdn.slidesharecdn.com/profile-photo-bijeugm-48x48.jpg?cb=1523455110 To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge. Ophtalmologyst.