Second sight is a form of extrasensory perception, the supposed power to perceive things that are not present to the senses, whereby a person perceives information, in the form of a vision, about future events before they happen (precognition), or about things or events at remote locations (remote viewing).
There is no scientific evidence that second sight exists. Reports of second sight are known only from anecdotal evidence given after the fact.
Second sight may have originally been so called because normal vision was regarded as coming first, while supernormal vision is a secondary thing, confined to certain individuals. An da shealladh or "the two sights," meaning "the sight of the seer", is the way Gaels refer to "second sight", the involuntary ability of seeing the future or distant events. There are many Gaelic words for the various aspects of second sight, but an da shealladh is the one mostly recognized by non-Gaelic speakers, even though, strictly speaking, it does not really mean second sight, but rather "two sights".[a]
An early example of symbolical second sight is found in the Odyssey, where Theoclymenus sees a shroud of mist about the bodies of the doomed Suitors, and drops of blood distilling from the walls of the hall of Odysseus. The Pythia at Delphi saw the blood on the walls during the Persian War; and, in the Argonautica of Apollonius Rhodius, blood and fire appear to Circe in her chamber on the night before the arrival of the fratricidal Jason and Medea. Similar examples of symbolical visions occur in the Icelandic sagas, especially in Njala, before the burning of Njal and his family. In the Highlands, and in Wales, the chief symbols beheld are the shroud, and the corpse candle or other spectral illumination.
Ranulf Higden, author of the Polychronicon (14th century), describes Scottish second sight, adding "that strangers setten their feet upon the feet of the men of that londe for to see such syghtes as the men of that londe doon"
In the early 20th century, Joaquin María Argamasilla, known as the "Spaniard with X-ray Eyes," claimed to be able to read handwriting or numbers on dice through closed metal boxes. Argamasilla managed to fool Gustav Geley and Charles Richet into believing he had genuine psychic powers. In 1924 he was exposed by Harry Houdini as a fraud. Argamasilla peeked through his simple blindfold and lifted up the edge of the box so he could look inside it without others noticing.
Science writer Martin Gardner has written that the ignorance of blindfold deception methods has been widespread in investigations into objects at remote locations from persons who claim to possess second sight. Gardner documented various conjuring techniques psychics such as Rosa Kuleshova, Lina Anderson and Nina Kulagina have used to peek from their blindfolds to deceive investigators into believing they used second sight.
- "The term da-shealladh (pronounced "dah-haloo"), often translated as "second sight", literally means "two sights". It refers to the ability to see apparitions of both the living and the dead. The taibshear (pronounced "tysher") is the seer who specializes in observing the energy double (taibhs). A dream or vision is a bruadar ("broo-e-tar"). The bruadaraiche ("broo-e-taracher") is more than a dreamer in the common sense; he or she is the kind of dreamer who can see into the past or the future."
- "online dictionary". Merriam-Webster.
- Regal, Brian (2009). Pseudoscience: A Critical Encyclopedia. Greenwood. p. 169. ISBN 978-0-313-35507-3.
- Chisholm, Hugh, ed. (1911). "Second Sight". Encyclopædia Britannica. 24 (11th ed.). Cambridge University Press. p. 570.
- Moss, Robert (2015). "Scottish dreaming: an ancestral call". Beliefnet, Inc. Retrieved March 27, 2016.
- Polidoro, Massimo (2001). Final Séance: The Strange Friendship Between Houdini and Conan Doyle. Prometheus Books. pp. 171–172. ISBN 978-1591020868.
- Joe Nickell. (2007). Adventures in Paranormal Investigation. The University Press of Kentucky. p. 215. ISBN 978-0813124674
- Gardner, Martin (2003). Are Universes Thicker Than Blackberries?. W. W. Norton & Company. pp. 225–243. ISBN 978-0393325720.