This lost me a few hours of play so I thought I'd mention it. In Chapter 2 if you speak to The Visionary before you do the Lost Lambs / Blood Curse quests it can send you into a loop where he won't talk about what he's supposed to when you're told to go see him and you'll be unable to continue. So if you come across him - he's the guy in a hut surrounded by candles where you get attacked by harpies - you might want to leave him be until you do the above mentioned quests and are sent to find him.
It might not happen for you, but thought I'd give a heads up anyway.
Yeah, It seem like talking to him out of sequence might cause problems - it was also possible when I was told to go find him or the relic seller that going to the relic seller first caused the problem. My problem was that he was basically saying what he should say when you are sent to him, and after you've helped the soldiers on the way who want you to take him the coin, but that's all he would say in a loop - and the soldier weren't there. I still can't be sure if it was me talking to him before I had the quests or going to the relic seller first was the issue. Lucky I had one autosave left from far enough back or I'd have had to restart the game.