Over the Garden Wall is SUCH a fascinating show to me for a myriad of reasons. But one of the things that stuck with me was the symbolism of the Woodsman and his lantern. TW for discussions on grief and unhealthy coping mechanisms (that I might get wrong, just as a warning).
I'm sure this has been said before, but to me it's just such a fascinating representation of how we unintentionally keep despair alive by clinging to our overwhelming grief of those we lost. Maybe I'm misinterpreting something or looking too deeply into it, but it's just. The lantern that the Woodsman keeps lighting in the hopes that his daughter's soul will be kept alive through it is, in actuality, keeping the Beast alive. And in a similar way I've read tales and actually studied grief theories about how people keep the memory of their loved one alive; at first, it's a good thing, and it can take however long or short you need to it be since grief seems to be something that generally never really goes away.
But there can come a point where all you live for is the dead, which is what the Woodsman was doing in laboring day and night to keep the lantern alive. And in doing so, you start to poison yourself and, rather than keeping the person you lost in living memory, you start to keep alive the despair and darkness. You start to keep alive the Beast rather than the soul of your daughter, in other words. Sometimes, it's intentional, though. "If I let go of this despair and anguish of mine, doesn't that mean I'll forever lose that person I loved?" And sometimes, it's unintentional.
The conclusion of it is that you have to let them go...you have to let that despair (not grief, but the poisonous and hopeless grief) go. Maybe, like Wirt did, through unflinching practicality and sheer knowledge rather than emotion. Or something else. But maybe, then, you'll find that when the lantern of your despair is gone, it'll be dark at first but you'll slowly start to see a grander light. And maybe, you'll find that your daughter is still alive anyway, in the light rather than in the darkness.