Time - "Time is not an object but an abstraction, hence it does not lend itself to imagery, which is why filmmakers are forced to represent the passage of time with contrivances that involve visible objects, such as calendar leaves blowing in the wind or clocks spinning at warp speed. And yet, predicting our emotional futures requires that we think in and about and across swathes of time. If we can't create a mental image of an abstract concept such as time, then how do we think and reason about it?... Studies reveal that people all over the world imagine time as though it were a spatial dimension, which is why we say that the past is 'behind' us and the future is 'in front of us'." From "Stumbling on Happiness" by Daniel Gilbert, Alfred A. Knopf, New York, 2006. Page 128.