This book forms the last of three. The first published was "_The Boats
of the 'Glen Carrig'_"; the second, "_The House on the Borderland_";
this, the third, completes what, perhaps, may be termed a trilogy; for,
though very different in scope, each of the three books deals with
certain conceptions that have an elemental kinship. With this book, the
author believes that he closes the door, so far as he is concerned, on a
particular phase of constructive thought.