I read somewhere that he won't give you the key to the seal "until the time is right". Well, I finally cleared the whole level of ghosts and the time couldn't be more right. What is the requirement? I've already rung the first bell and got as far as clearing the Depths to get into Blighttown. Do I need to do Blighttown first?
Ah, I'm in the wrong area for what I want to do. I need to get deeper into Blighttown first. I thought that since the ghosts were easier to kill than mobs in Blighttown, New Londo was the next progression.