> you don't understand a concept unless you can ELI5 Do you have any particular reason to believe that there are no ideas which are simply difficult? For examp

> you don't understand a concept unless you can ELI5 Do you have any particular reason to believe that there are no ideas which are simply difficult? For example, I assert that the Monadicity Theorems are difficult and defy easy explanation; and general relativity is difficult and defies easy explanation. It's not that we don't want to explain these things simply: it's that we can't because they just have too many prerequisites. There are some open problems in exposition (such as forcing, which ought to admit an intuitive explanation but no-one has yet found one), but knowing that we don't yet know how to explain something simply is not the same as refusing to explain something simply.