Board Thread:Show-Related Questions and Answers/@comment-25491743-20150817210639/@comment-25375217-20151226195750

(Ik this is really old but I'm going to respond to it anyway)

I would say that Pandora's Box trapping the "greatest darkness" is actually a specific person or creature who was trapped many years ago and may or may not (leaning towards not) be released at some point on Once to become a villain. Someone like Dracula or another Chernabog, who is really powerful and threatening. But like the hat, the Box would have its limits and, while Dracula is really powerful and threatening, he isn't the same as the literal Darkness, and trying to trap it would have worked just as well as the hat.

So why didn't they try it? Well, we know the hat was made by Merlin specifically for trapping powerful beings. The Box, we don't really know where it came from, and freeing someone from it isn't particularly hard. So I would say it makes perfect sense that they would choose to use the hat, particularly since it was the Apprentice's idea in the first place, and he has seen the hat in use for many years. And it might not have been able to target just the Darkness. It might have just sucked Gold in too, like it did before.

So yeah, in universe there are a lot of ways to explain it. Out of universe... well, what Eskaver said.