Then you certainly know more about religious iconography than I do. Nevertheless, if you're going to make a claim as extreme as saying that iconography doesn't

Then you certainly know more about religious iconography than I do. Nevertheless, if you're going to make a claim as extreme as saying that iconography doesn't (in the majority of cases, to a large extent) require prior understanding, you'd do better to make some sort of argument or cite some sort of evidence rather than merely asserting authority. However, it may just be a misunderstanding. The quote that you said was "absolutely not true" had two statements: > No icon anywhere is intuitive. They're all learned. I'm not saying that symbols, found in religious icons or elsewhere, can't be "intuitive", in the sense that there's some underlying logic or they're otherwise easier to understand than a set of symbols picked at random. (That said, many of them, like the aforementioned Eastern Orthodox clothing colors, do seem fully arbitrary.) I'm just saying that they're also "learned", i.e. you can't (fully) make sense of them without prior understanding. By the way, your mention of radioactivity reminds me of the US government's attempt to design markers for nuclear waste sites which can be understood many thousands of years into the future, without a common language – e.g. as described in this article: https://www.ft.com/content/db87c16c-4947-11e6-b387-64ab0a67014c https://www.ft.com/content/db87c16c-4947-11e6-b387-64ab0a670... This is an interesting problem precisely because it is hard to unambiguously convey abstract concepts using iconography without context – even a concept as simple as "this place is dangerous". Thus, the proposals end up being rather complex.