Greek in the Roman Empire

In English we have the saying "it was Greek to me" first recorded (though almost assuredly not first used) in "Julius Caesar" by Shakespeare (I know German has 'das kommt mir Spanisch vor,' Latin had 'Graecum est, non legitur,' and other languages have similar expressions about Chinese, Arabic, etc.).

Casca, a Roman, overhears people speaking Greek and says he didn't understand. However, some reports have Caesar's actual historical last words as the Greek "kai su, teknon?" rather than the Latin "et tu, Brute?"

So, my question: What was the status of the Greek language in the Roman Empire? Did the aristocracy typically learn it? I know it ended up being the lingua franca of the Eastern Empire, but what about in the West?

The Latins had Greek in high steem, even more than Latin sometimes. All rich people in Rome had Greek slaves to teach their childre. So it's strange that Julius Caesar didn't know Greek. Greek for the Latins was like French for the Europeans ultil a few years ago.

Caesar probably did know Greek, it was his friend (and conspirator) Casca who Shakespeare portrayed as unable to speak Greek.

Greek was in Rome just like English today in Continental Europe, the language any educated person was supposed to know well.

Caesar's famous last words were "Tu quoque mi fili" in Latin translation, but the fact that he instinctively used Greek in such a moment is highly emblematic.

The poet Juvenal was famous for loudly criticizing the 'hellenomania' of the elite but he was pretty much alone.

Romans of the upper class were often interested in philosophy but found their own language inadequate — they argued in Greek.
Strangely, Latin emerged as a philosophic medium quite late in history, thanks to Christianity.

Shakespeare was pretty intellectually challenged, so it's not surprising he didn't get his history right.

Was Seneca the only Latin philosopher?

Well new ideals were incorporated into the Roman Empire when the Romans invaded Greek ie. Maths, etc.

I guess thats why in English - eg. description of art or food, we tend to use terms of French/Latin orgins, as most famous arts and foods did come from Latin countries.

Another one was the use of words of Dutch origins in the field of boating.

These days it's English terms entering other languages in most cases remaining in it's Anglicised form or near it when dealing with technology for example.

<<I guess thats why in English - eg. description of art or food, we tend to use terms of French/Latin orgins, as most famous arts and foods did come from Latin countries.
>>

you mean like spaghetti and pizzas?

Skippy : « Caesar probably did know Greek [...] ».

Oui, certainement. En tout cas, aux dires de Suétone, les dernières paroles de César furent ces trois mot grecs, « Kαὶ σὺ τέκνον ! », adressés à Brutus.