The end of the road

Having called sinners to follow him, having explained what it looks like to depend upon him entirely, having underscored the need to put God and his kingdom before all else, our Lord reminds us that he is on that path of faith and obedience. His disciples must go up with him to Jerusalem, where he will suffer and die at the hands of the Gentiles. Why did the disciples not grasp this? Perhaps more importantly, do we?