Out of Context: On Intuition (Definitions)

"By intuition is frequently understood perception, or the knowledge of actual reality, the apprehension of something as real. […] Intuition is the undifferentiated unity of the perception of the real and of the simple image of the possible. " (Benedetto Croce, "The Essence of Æsthetic", 1921) 

"A new idea comes suddenly and in a rather intuitive way. But intuition is nothing but the outcome of earlier intellectual experience." (Albert Einstein, [Letter to Dr. H. L. Gordon] 1949)

"Instinct, intuition, or insight is what first leads to the beliefs which subsequent reason confirms or confutes; [...] (Bertrand Russell, "Our Knowledge of the External World", 1914)

"Intuition is the collection of odds and ends where we place all the intellectual mechanisms which we do not know how to analyze or even name with precision, or which we are not interested in analyzing or naming." (Mario Bunge, "Intuition and Science", 1962)

"Mathematical intuition is more often conservative than revolutionary, more often hampering than liberating." (Freeman Dyson, "Mathematics in the Physical Sciences", Scientific American Vol,. 211 (3), 1964)

"That is to say, intuition is not a direct perception of something existing externally and eternally. It is the effect in the mind of certain experiences of activity and manipulation of concrete objects (at a later stage, of marks on paper or even mental images)." (Philip J Davis & Reuben Hersh, "The Mathematical Experience", 1981)

"Intuition is the art, peculiar to the human mind, of working out the correct answer from data that is, in itself, incomplete or even, perhaps, misleading." (Isaac Asimov, "Forward the Foundation", 1993)

"Intuition is forged in the hellish fires of the everyday world, which makes it so eminently useful in our daily struggle for survival." (Vincent Icke, "The Force of Symmetry", 1995)

"Intuition isn't direct perception of something external. It's the effect in the mind/brain of manipulating concrete objects - at a later stage, of making marks on paper, and still later, manipulating mental images. This experience leaves a trace, an effect, in your mind/brain." (Reuben Hersh, "What Is Mathematics, Really?", 1998)

"Mathematical intuition is the mind’s ability to sense form and structure, to detect patterns that we cannot consciously perceive." (Ian Stewart, "Visions of Infinity", 2013)

"An intuition is neither caprice nor a sixth sense but a form of unconscious intelligence." (Gerd Gigerenzer, "Risk Savvy", 2015)

"Intuition is a spiritual faculty and does not explain, but simply points the way." (Florence S Shinn)

"Intuition is a method of feeling one's way intellectually into the inner heart of a thing to locate what is unique and inexpressible in it." (Henri Bergson)

"Intuition is not infallible; it only seems to be the truth. It is a message which we may interpret wrongly." (Christina Stead)