The only "intuitive" interface is the nipple. After that it's all learned.
This is usually attributed to one Bruce Ediger (though at least one person thought it was originally said by Steve Jobs, a manufacturer of fine computers), and refers to the frequent (and invariably inaccurate) description of computer user interfaces as "intuitive". But in 2001, Bruce denied that it was original to him. This made me wonder what the history of the quote was.
My first stop was a dictionary of quotations, but that doesn't have it at all. Perhaps it is indeed relatively recent, then.
I can get back as far as August 1994, where Scott Francis suggests the nipple as the only intuitive interface, in response to "There really is no user interface metaphor that is truly intuitive." The idea is there, but the exact form is not. (And of course, nipples aren't metaphors, at least in this context.) To get close to the usually-quoted form of words, the earliest I can find is this one from January 1995, by one Jay Vollmer. He said:
Actually, the only truly intuitive interface is the nipple.
Did Bruce see this post and like it, or did he see the idea somewhere else? It's not really possible to tell from Google's archive. At any rate, he started using variants of it shortly afterwards. For instance, in February 1995:
It's an old saw, I know, but the only really, truly "intuitive" interface is the human nipple.
Slightly later the same month, we see a variant on the "it's all learned" theme from one Taylor Hutt:
I argue that no computer interface is intuitive -- none; they are all learned.
In April 1995 Bruce is back:
By this definition, the nipple is the only "intuitive" user interface.
Basically, the only "intuitive" interface is the nipple. After that, it's all learned.
So perhaps Bruce does have the best claim to this form after all? Maybe. At any rate, I think I prefer his 2001 version:
There is no intuitive interface, not even the nipple. It's all learned.