"There is always in childhood one moment when a door opens and lets in the future." (Graham Greene. Posted as a prompt on email@example.com)
My first response to this quote was, "Just one?" I just can't wrap my head around the idea of there being one door leading the way to one sole path in life which leads to one destination. (Tangent: just how would a person wrap their head around something? Like a towel? A scarf? A big, warm blanket? A flour tortilla?)
Life itself makes it impossible to have just one door. In folklore and mythology, doors are important places. They are thresholds, boundaries and the "in between." The boundary between the everyday world and Faery. The boundary between waking and dreams. The boundaries between youth and adolescence as well as between adolescence and adulthood (whatever that is.)
Ordinary, everyday decisions can be doors and it could be said we're constantly teetering in the "in between." Thought of in this way, "what if?" becomes a far more potent and dangerous question.