Happy Saint Patty's Day! The national horse of Ireland is, of course, the handsome, heavy-boned Irish Draft (or, in more local parlance, the Irish Draught Horse). But did you know that the breed was developed from the now-extinct Irish Hobby horse? And from the Hobby horse arose the expression, "to ride one's hobby horse," meaning to follow one's passion. The term was then shortened to just having or enjoying a "hobby." So the English language owes the word "hobby" to an Irish horse breed…