Effective analogy for showing what prosopagnosia is like

[Update: the linked page can now be accessed here]

Prosopagnosia is 'face-blindness' - the inability to recognize other humans by their faces. This page is a very effective description of what it's like, written by a sufferer.

They say good writing shows rather than tells, and that's what that pages does, using a very effective analogy -- to show you what it's like to have prosopagnosia.

If individuals were rocks, then it's like having to remember the characteristics of each rock, and try to realise when you come across this rock again, from your memories. The page uses photos of different rocks so you can see for yourself the sorts of difficulties involved.

There's a lot of complications you probably wouldn't think of, which the page demonstrates well. E.g. when someone gets a haircut - as demonstrated by the rock being obscured by a bit of foliage.