Most people feel precisely this way about ghosts, though few are candid enough to acknowledge it. In broad daylight, or when seated before a cheery fire among a group of congenial friends, it is easy to be skeptical, and to regard ghosts as mere products of imagination, superstition, credulity, hysteria, or indigestion. But it is notorious that even the most skeptical are liable to creepy sensations and sometimes outright panic if they experience "uncanny" sights or sounds in the darkness of the night, or in lonely, uninhabited places. Churchyards have never been popular resorts of those who go for a stroll in the cool of the evening. And let a house once get the reputation of being "haunted," it is next to impossible to find tenants for it. Yet this almost universal attitude is entirely and fundamentally wrong. There is no reason for being afraid of ghosts, and there are many reasons for believing in them. I do not, of course, mean to say that all ghosts are real ghosts. There are plenty of bogus ghosts, and there always will be, as long as men eat and drink too much, play practical jokes on one another, and allow their houses to become run down and infested by rats and mice. A single rat, scampering at midnight over the loose planks of an old attic, has often been quite sufficient to produce a counterfeit "poltergeist," or troublesome ghost, of a highly impressive character. So, too, a pillow-slip swaying from a clothesline is apt to seem most ghostly to a gentleman returning home from a late supper. Ghosts, like much else in this amazing world of ours, have to be pretty sharply scrutinized. And the point is that, after centuries of contemptuous neglect, they have at last been made the subject of investigation by men and women competent for the task--persons trained in the cautious methods of scientific inquiry, and insisting upon the strictest evidential standards, but devoid of prejudice or prepossession. Their researches are still in progress, but they have already demonstrated that amid a multitude of sham ghosts there are perfectly authentic apparitions, displaying credentials too convincing to be denied. What is still more important, the labors of these scientific ghostologists--especially of those enrolled in the famous English Society for Psychical Research--have also resulted in throwing much light on the nature, origin, and habits of real ghosts. Usually, it seems, a genuine ghost is seen or heard but once or twice, and then, having accomplished its purpose, it departs to return no more. But there are plenty of well-attested cases in which a ghost attaches itself to a house or family, and keeps up its haunting for years, sometimes for centuries.