Doom and hope, misery and joy, are but two sides of the same mirror to this ancient force that has withstood the annihlation of an entire culture..
You receive a vision of a rooftop "somewhere close by", where a rare moss grows; in the vision, you know the moss is suitable for greatly enhancing the effects of certain types of potions. Now go and find that rooftop. Don't fall off. (Of course, rooftop runners *will* be taken for miscreants by the local City Watch....)