Full Idea
There is hardly a word in the language - be it an adverb, preposition, conjunction, or what have you - that is devoid of metaphorical potential.
Gist of Idea
Hardly a word in the language is devoid of metaphorical potential
Source
Stephen Yablo (Apriority and Existence [2000], §12)
Book Reference
'New Essays on the A Priori', ed/tr. Boghossian,P /Peacocke,C [OUP 2000], p.213
A Reaction
Yablo goes on to claim that metaphor is at the heart of all of our abstract thinking. 'Dead metaphors' (like the "mouth" of a river) sink totally into literal language. I think Yablo is on the right lines.