The big door in the sewers

[bonipolo]

I'm not sure if they've asked this already but I can't figure out how to open the big door in the sewers, if it's even possible to open it.
So far I tried using Wilbur's Necronomicon book but it didn't work, tried the priest's book plus the talisman same result, re-read the log on the work bench and thought that maybe I just needed to have a headache, meaning low sanity, even got the depressed status but none of it worked.
Is it strength that I need or do I need to get the extreme depression status?