Full Idea
Ranking desires in order of preference is no help, because a person who wants one thing more than another may not regard the former as any more important to him than the latter.
Gist of Idea
Ranking order of desires reveals nothing, because none of them may be considered important
Source
Harry G. Frankfurt (The Reasons of Love [2005], 1.5)
Book Reference
Frankfurt,Harry G.: 'The Reasons of Love' [Princeton 2006], p.12
A Reaction
A salutary warning. Someone may pursue something with incredible intensity, but only to stave off a boring and empty existence. The only way I can think of to assess what really matters to people is - to ask them!