The literal meaning of metaphor: X = Y

Author and aphorist James Geary describes how metaphor may lead to unexpected decision making in this just released TED video.

The elliptical faculty of metaphor enables ranking and comparison; it is both richly informative and misleading, as Geary suggests. In contrast to an earlier understanding, recent research has also shown that we are born with some innate sense of number and language - we are not blank slates onto which all subsequent knowledge is imparted afresh, but equipped from the beginning with this ability to relate things, one to another.

If the subject of this interaction between mind and world interests you, check out Embracing the Wide Sky by prodigious savant and synesthete Daniel Tammett, who describes the sense-making power of language and number from his rather unusual and direct vantage. Highly recommended.