Full Idea
Descartes argued (in 'The World') that just as words refer to objects, but they do not resemble them, in the same way, visual images or other sensory inputs relate to objects without depicting them.
Gist of Idea
Descartes said images can refer to objects without resembling them (as words do)
Source
report of René Descartes (works [1643]) by Richard Tuck - Hobbes
Book Reference
Tuck,Richard: 'Hobbes: a very short introduction' [OUP 2002], p.21
A Reaction
This strikes me as a rather significant and plausible claim, which might contain the germ of the idea of a language of thought. It is also the basis for the recent view that language is the best route to understanding the mind.