Unlike other realist writers of the time who enjoyed writing about Europe and thought that America wasn't as developed, Mark Twain created his American characters in Europe in such a manner to mock everything and everyone, showing Americans often as people who don't know how to behave, while at the same time showing Europeans as overrated, and not generally as advanced as they would have you think.
There are only six modern Celtic languages, they are Welsh, Cornish, Breton, Irish, Manx, and Scottish Gaelic.
As you can see Greek is not included in the modern Celtic languages, so Greek is not a Celtic language.
Wait ... who is this joe you speak of?
It is very unique and mayan