The saddest of all of these lines. After the soothsayer had told him, Beware the Ides (15th) of March, some time before, Caesar went about his business on this day, which seemed like every other day. For his cabinet to conspire to kill him was not so surprising, their reasons were understandable. But for Caesar to look around, seeing his beloved friend, Brutus, participating, added just a final heartbreak to his murder. Even you, Brutus?
Brutus was a turncoat from Caesars vanquished rival, Pompeii, it's hardly surprising that he betrayed Caesar too. Though Shakespeare fans know he got his comeuppance in the end...
Given the Shakespearian context, I only wish that the quote had been: Proximo satis pro administratio. (Close enough for government work.) Think about it . . .
So much said in so few words. And you, Brutus?...The essence of betrayal! Probably wasn't too much fun to be on the receiving end of that kind of backstabbing, but Caesar can take comfort in the fact that the darkest circle of Hell is reserved for two of his assassins.