Metaphors are very powerful things. They are cognitive super conductors that allow us to process and comprehend complex, metaphysical and conceptual ideas with succinct efficiency. Moreover the power of metaphor goes beyond just the condensing of information and allows for emotional weight to be embedded into meaning.
I wrote last year of the types of metaphor in cinema - cognitive, emotive and, of course, visual. But at the core of what a metaphor is nothing explains so succinctly as this TED talk video from John Geary.
In this compelling 10 min presentation, Geary distills the importance and power of metaphor for all human society - present in our everyday language and shaping (not always for the better) the way we see the world and behave in it.
Whilst never mentioning screen media or narrative storytelling the Ideas the video contains speak to heart of cinema.
Having spent many years reading and developing screenplays, writing coverage for scripts, assessing treatments and judging writing competitions, I can say with certainty that the two elements unsuccessful or uncompelling screenplays lack are Metaphor and Subtext. Watching this 10min video might well be the solution to part of this problem.