Apparitions appear. Apparitions are not necessarily Ghosts. Superstition, Common-sense, and Science. Hallucinations: their kinds, and causes. Aristotle. Mr. Gurney's definition. Various sources of Hallucination, external and internal. The Organ of Sense. The Sensory Centre. The Higher Tracts of the Brain. Nature of Evidence. Dr. Hibbert. Claverhouse. Lady Lee. Dr. Donne. Dr. Hibbert's complaint of want of evidence. His neglect of contemporary cases. Criticism of his tales. The question of coincidental Hallucinations. The Calculus of Probabilities: M. Richet, MM. Binet et Fere; their Conclusions. A step beyond Hibbert. Examples of empty and unexciting Wraiths. Our ignorance of causes of Solitary Hallucinations. The theory of 'Telepathy'. Savage metaphysics of M. d'Assier. Breakdown of theory of Telepathy, when hallucinatory figure causes changes in physical objects. Animals as Ghost-seers: difficult to explain this by Telepathy. Strange case of a cat. General propriety and lack of superstition in cats. The Beresford Ghost, well-meaning but probably mythical. Mrs. Henry Sidgwick: her severity as regards conscientious Ghosts. Case of Mr. Harry. Case of Miss Morton. A difficult case. Examples in favour of old-fashioned theory of Ghosts. Contradictory cases. Perplexities of the anxious inquirer. Only one thing is certain about apparitions, namely this, that they do appear. They really are perceived. Now, as popular language confuses apparitions with ghosts, this statement sounds like an expression of the belief that ghosts appear. It has, of course, no such meaning. When Le Loyer, in 1586, boldly set out to found a 'science of spectres,' he carefully distinguished between his method, and the want of method observable in the telling of ghost stories. He began by drawing up long lists of apparitions which are _not_ spectres, or ghosts, but the results of madness, malady, drink, fanaticism, illusions and so forth. It is true that Le Loyer, with all his deductions, left plenty of genuine spectres for the amusement of his readers. Like him we must be careful not to confound 'apparitions,' with 'ghosts'. When a fist, applied to the eye, makes us 'see stars'; when a liver not in good working order makes us see muscae volitantes, or 'spiders'; when alcohol produces 'the horrors,'--visions of threatening persons or animals,--when a lesion of the brain, or delirium, or a disease of the organs of sense causes visions, or when they occur to starved and enthusiastic ascetics, all these false perceptions are just as much 'apparitions,' as the view of a friend at a distance, beheld at the moment of his death, or as the unrecognised spectre seen in a haunted house.