We get the English saying, "He saw the handwriting on the wall" from another story in Chapter 5 where the king was having a party and a hand appeared and wrote some strange words on the wall. Daniel was able to tell the king that this meant that he was about to be killed and another king would take his place. We use this phrase "handwriting on the wall" to mean that someone sees that something bad is about to happen or something good is about to end.