So when this mysteriously titled art book, “Cappy,” written by Terry Wallace, an East Hampton gallerist, crossed my desk, I asked myself, who is Cappy? I was quickly reminded of an old adage regarding artists’ monographs — beware the dust jacket of an art book that doesn’t illustrate art. The cover’s photograph is of a craggy middle-aged Scandinavian fisherman type, squinting directly at me and the camera. And the illustration on the back is a haunting photograph of the same person as an ancient mariner.