The seer is blocking you from getting that beautiful tarantula jar.
He said that he is preparing a speech and would need fancier robe. Get him a fancier robe
Oh, he threw you out. Maybe you can access his room somewhere else?
Like the next room. The ghost room. The ghost should be.. umm.. occupied and you can get past it. Grab the tarantula jar through the window.
With a tool that is designed to remove corks, of course.
Use the corkscrew that you can find from the restaurant.