The dilemma is that as thing become more abstract, making a "self explanatory" icon requires prior knowledge of other abstract concepts from the user.

For example the cloud "obviously" means something on the internet, something like online storage, and you can derive a lot of "self explanatory" icons from there. But what about those who don't understand it?

Funnily enough, I once saw a cloud icon on a piece of software, I thing it was mapping software, I instantly though about something about the internet. It took me a bit of time to realize it was for the weather, I mean, actual clouds.

> A good icon is self explanatory.

So said the ancient Egyptian scribes, and yet they wrote a Rosetta Stone.

Is there a good icon for "save" action, that will work even for people that never see floppy disk?

One could argue if that actually makes it a less effective icon.

And it's not the only case where something similar happens:

https://ux.stackexchange.com/questions/90445/mail-icon-is-th...

“Self explanatory” doesn’t exist. There are only icons that people have seen before (and recognize), and those they haven’t.