The term delusion It has its origin in Latin illusĭo. It is a concept or an image that arises by the imagination or through a deception of the senses , but that has no true reality.

Linked to the senses, an illusion is a perception distortion . One can speak of optical illusions (the most usual), olfactory illusions, auditory illusions, gustatory illusions or tactile illusions.

The optical illusion leads to perceive reality in a distorted way through sight. This distortion can be caused by physiological (through excessive stimulation in the eyes or in the brain) or cognitive (depending on the way we perceive the world).

Among the most significant and famous optical illusions, we should highlight, for example, mirages. These occur as a result of the perception of objects that we see far away and that when reflected on a smooth surface give rise to a liquid surface that does not really exist. The clearest example of mirage is that which takes place in the deserts where the circumstances to which the individual is subjected and the characteristics of the place produce that he sees things that do not really exist.

The hologram is another important type of optical illusion. This we can say that it is the result of a photographic technique that allows the development of three-dimensional images. However, we cannot forget other illusions of this type such as irradiation, grid illusion or stereogram.

Mental illusion, also called mentalism, is, on the other hand, that science or art that makes whoever develops it use suggestion, mental agility or scenic magic to be able to undertake mental control, psychokinesis, clairvoyance or precognition. We can also establish that this is a branch known as illusionism.

For the psychology , the illusion is a hope that has no foundations . In a symbolic sense, it can be said that an illusion is a mirage (something that seems real but is not): “I had the illusion of solving things with her but I realized that it is impossible”, "I thought I could win the race, although it was just an illusion".

It should be noted that the positive meaning of illusion (“My biggest illusion is to travel to Europe to meet my grandfather again”) only exists in the Spanish language. In others tongues , the term is always related to what lacks support.

It is known as illusionism , finally, to the scenic art that consists of using various means to create the illusion of something impossible happening from the logical point of view: "Last night I saw an illusionist on TV who cut a girl in half".

Many are the characters that throughout history have become a reference within illusionism. However, among all of them Frenchman Jean Eugène Robert-Houdin acquires special relevance, who has been qualified as the father of modern magic. Among the tricks he performed throughout his career and which later became general, he highlighted the one in which a person from the audience shot him and he not only was not injured but appeared with the bullet between his teeth.