Two geese labored to gain altitude, one rising into place at the wing tip of the other, the pair joined by a third, and more, the geese languidly forming a V in the sky—not because of a leader but because patterns of behavior could emerge as surely as a convergence of light and moisture could throw a rainbow across the sky. The geese made their way south across a brilliant sunrise—each bird carrying the logic of the flock. And the logic of its lice. And the logic of the cells within the lice. And the logic of the virus within the cells, churning the tumblers on their biological locks. The odds of hitting the jackpot on a penny slot machine were
one in a 1,000; a player pulling the handle 10 times a minute
would hit the right combination every 100 minutes. But 1,000
players would produce 10 winners every minute, whether those
players were people cycling through combinations on a slot
machine, or the genetic stuff of a bird.

A flu infection can produce 200 trillion new viruses a week.
Some combinations would be stymied, freezing into death as
quickly as they were born, while others opened up new paths for life the way a single log in a jam can suddenly click out of place and allow a mighty river to flow within viruses within lice within geese within flocks—like these—all over the world, on the move, laboratories in the sky, crossing borders, landing in forests and public parks and backyards and waterways and wading pools….