Why listen to James Marsh? Because he knows about love and encyclopedias.    He grew up in The Junction district of Toronto surviving a difficult childhood, and began his career in publishing at Holt Rinehart and Winston where he was editor of a Centennial history of Canada entitled Unity and Diversity. He later became executive editor of McClelland and Stewart's Carleton Library Series, after which he was hired by Mel Hurtig as editor-in-chief of The Canadian Encyclopedia - the biggest printing/publishing endeavour in Canadian history.    We talk about his memoir Know it All: Finding the Impossible Country and about what he found; about encyclopedias striving for ideals; about historian Ramsey Cook and limited identities; selection by community; post-Centennial enthusiasm for Canada; economic nationalism; selling 250,000 sets of The Canadian Encyclopedia and then putting it on-line and making it "engaging;" the importance of conversation to democracy; Alberta premier Peter Lougheed; the woman with the two colour eyes; and the gift of friendship.