Full Idea
An idea can be like nothing but an idea.
Gist of Idea
An idea can only be like another idea
Source
George Berkeley (The Principles of Human Knowledge [1710], §08), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 43 'Mean'
Book Reference
Potter,Michael: 'The Rise of Anaytic Philosophy 1879-1930' [Routledge 2020], p.292
A Reaction
I take this to be relevant to the correspondence theory, but also to be one of Berkeley's best observations. We understand ideas, but we can't map them onto the world (because they are not maps!). ...But then how is one idea like another? Hm.
Related Idea
Idea 6277 Correspondence between concepts and unconceptualised reality is impossible [Putnam]