Quicksilver

It's a day to feel grateful ... and to ponder gratitude. One thing I've noticed is how mercurial it can be, how it can lie leaden in the heart until something happens — a friend calls, a baby laughs, the dough rises — and suddenly it flies up, a bird with fluttering wings. 

You try to catch it as it soars, but soon it's gone again. Was it really there, or were you just imagining it? 

I choose to believe the former.  Its sightings may be sporadic, but its presence is real.