The spirit of to-day is terrifyingly visible or invisible at will. The dreadful presence of a ghost that one cannot see is more unbearable than the specter that one can locate and attempt to escape from. The invisible haunting is represented in this volume by Fitz-James O'Brien's _What Was It?_ one of the very best of the type, and one that has strongly influenced others. O'Brien's story preceded Guy de Maupassant's _Le Horla_ by several years, and must surely have suggested to Maupassant as to Bierce, in his _The Damned Thing_, the power of evil that can be felt but not seen. The wraith of the present carries with him more vital energy than his predecessors, is more athletic in his struggles with the unlucky wights he visits, and can coerce mortals to do his will by the laying on of hands as well as by the look or word. He speaks with more emphasis and authority, as well as with more human naturalness, than the earlier ghosts. He has not only all the force he possessed in life, but in many instances has an access of power, which makes man a poor protagonist for him. Algernon Blackwood's spirits of evil, for example, have a more awful potentiality than any living person could have, and their will to harm has been increased immeasurably by the accident of death. If the facts bear out the fear that such is the case in life as in fiction, some of our social customs will be reversed. A man will strive by all means to keep his deadly enemy alive, lest death may endow him with tenfold power to hurt. Dark discarnate passions, disembodied hates, work evil where a simple ghost might be helpless and abashed. Algernon Blackwood has command over the spirits of air and fire and wave, so that his pages thrill with beauty and terror. He has handled almost all known aspects of the supernatural, and from his many stories he has selected for this volume _The Willows_ as the best example of his ghostly art.