Full Idea
I cannot think of a single philosophically interesting concept that has been successfully and nontrivially analysed to most people's satisfaction.
Gist of Idea
No one has ever succeeded in producing an acceptable non-trivial analysis of anything
Source
Michael Lockwood (Mind, Brain and the Quantum [1989], p.121)
Book Reference
Lockwood,Michael: 'Mind,Brain and the Quantum:The Compound 'I'' [Blackwell 1991], p.121