Greek must be one of the tougher, maybe the toughest?, languages to learn because it is used as the example for something that is nearly incomprehensible because it is so complex. Apparently even Shakespeare found it difficult to master as he used it in Julius Casear in mostly the same way we use it today.
"CASSIUS: Did Cicero say any thing?
CASCA: Ay, he spoke Greek.
CASSIUS: To what effect?
CASCA: Nay, an I tell you that, I'll ne'er look you i' the face again: but those that
understood him smiled at one another and shook their heads; but, for mine own
part, it was Greek to me."