Full Idea
Difficulties of vagueness are presented by the question 'When did Rembrandt become clearly old?', and the iterating question 'When did he become clearly clearly old?'. This is the phenomenon of higher-order vagueness. The language of vagueness is vague.
Gist of Idea
Asking when someone is 'clearly' old is higher-order vagueness
Source
Timothy Williamson (Vagueness [1994], Intro)
Book Reference
Williamson,Timothy: 'Vagueness' [Routledge 1996], p.2
A Reaction
[compressed] I presume the bottom level is a question about Rembrandt, the second level is about this use of the word 'old', and the third level is about this particular application of the word 'clearly'. Meta-languages.