What is the law of dreams?

I've just finished reading Peter Behrens' The Law of Dreams for my next book discussion group. It's a wonderfully evocative title, but what does it mean? In the book, there is a line "the law of dreams is to keep moving." That seems to fit the story: this is the story of movement, of journey. The main character Fergus moves from Ireland in the 1840's to America via Liverpool, England. It's also a people's journey from poverty and famine to survival in faraway places. It's also my family story for I have ancestors who came to Canada from Ireland in those lean years. Perhaps that is why this book resonates so powerfully with me.