Consider the past. It’s something we’re told not to dwell on, but research makes it clear that thinking in the past tense can lead to a greater understanding of ourselves. For instance, nostalgia—contemplating and sometimes aching for the past—was once considered a pathology, an impairment that diverted us from current goals. Scholars of the seventeenth and eighteenth centuries thought it was a physical ailment—“a cerebral disease of essentially demonic cause” spurred by “the quite continuous vibration of animal spirits through [the] fibers of the middle brain.”
