Creativity, according to the creative – what they say is the essence of creativity..:

Any mental occurrence simultaneously  associated with two habitually incompatible contexts.  Arthur Koestler

That moment of insight becomes the creative act as a joining of two previously incompatible ideas. Lyall Watson

The association of two, or more, apparently alien elements on a plane alien to both is the most potent ignition of poetry. Comte de Lautrémont

Perceiving analogies and other relations between aparently incongruous ideas or forming unexpected, striking or ludicrous combinations of them. Rem Koolhaas

Invention or discovery takes place by combining ideas. Jacques Hadamard

The unlike is joined together, and from differences results the most beautiful harmony. Heraclitus

Where the imaginative and the functional fuse and finally become indistinguishable. Milton Glaser

How such connections spring to mind are guesswork but they seem to favour those who have a promiscuous curiosity and chronic attraction to problems.