I've read that philosophers claim that the sorts of things that can be true are things that could be potentially talked about in words. It also seems held that truth is essential to knowledge. Hence, it seems that the claim is that language is essential to knowledge. But I was looking at an intricate (but ugly) carpet yesterday, and it really did seem to me that it wordlessly expressed knowledge, as much as many sentences do. Why cannot a visual idea express knowledge as well as a word idea?