Greek to me

It’s all Greek to me means that something is as incomprehensible as Greek would be to someone who did not know the language. Shakespeare uses the expression in Julius Caesar (c. 1599) Act I, Scene II, “For my own part, it was Greek to me.” There is, however, an earlier citation, George Gascoigne (1573) in Supposes I: “This geare is Greek to me” where geare is a now obsolete word for matter or subject.