Behold the dart.

At one time crossbow bolts were cut down to play games instead of killing people.

It is held by a man with a whiskey Coke in his off hand. As he sets the drink on a table he gives a nod and a wink to a young woman talking to her friends. He slides his fingers along the silver-nickel barrel, traces the stabilizing shaft and pear shaped curve of the flight, and steps to the throw line. He feels the weight of a matching pair in his back pocket and the weight of the drink in his gut. The board sways in front of him, reminding him of how the woman moved on the dance floor.

The half-life of lead found in bones is between 20 and 30 years.

The dart rocks with the hand as it comes back. Forward, slow. Back and forward. Release. The fletching sets the spin as gravity attempts to pull the dart down, backward. But this is impossible. The dart is forced forward, through the air, currents sliding along its contours. Looking back we see the point, see the shooter with his arm outstretched holding his breath, the girl at the table checking her phone, the man's friends standing behind him, laughing. Each secretly ashamed of their hope for a sin. Miss the mark. They each cast their thoughts at the flying missile. Miss the mark. The dart dips from triple twenty past the bullseye.

What we don't see is the true course because it has slipped quite cleanly through time.

Behold, the dart is now a bird.

France killed turkeys and put their feathers on the end of wooden sticks, whittled to a point.

It does not see the man or the woman. It is no longer made of metal and polymers. It is free in the air and flaps its wings. It sings a song. Wind blows hard over its blue and white feathers as it catches an updraft. We do not see as the bird sees, the crushing vibrancy of ultraviolet wavelengths, rolling beneath shimmering currents and eddies of air. We see brown and black shingles of houses, red slate, green grass, fields interrupted by fences and thick forests.

The graph of half-life decay reaches toward an asymptote, a smooth curve that will never quite reach zero.

There is a tall tree by a stream. The bird seeks a home and a bath. It lands by the stream and digs its beak into the wet earth, pulling up a fat worm. After the worm is gone it hops into the flowing water. If we were in front of the bird we would see the point of its beak, the tree looming overhead with the shooter's initials carved beside the woman's from a time when they were just boy and girl, and a large cat slinking through the tall reeds.

The cat pounces.

Behold, the bird that was a dart is now a rocket.

The first darts were weighted with lead, exposure to which can cause delirium, memory loss, and death.

The man is now a boy and watches eagerly as the TV flashes images that make the boy dream of being an astronaut. It is July, and hot, like the flames shooting from the bottom of the rocket. The rocket broke from its moorings as the smoke billowed out below like an upside down volcano exploding. Up it went, burning through the sky, a shot from a Roman candle, hell-bent to get away from everything safe and familiar.

Graphs can be drawn using geodesic polar coordinates, which bear visual similarities to a dart board.

The rocket climbs and curves, finally entering space, achieving weightlessness. As it blasts onward it begins to break apart, section after section. If we were in front of the rocket we would see the point, looming larger. The empty stages shrink away in the distance. The final stage streaks onward.

What we don't see is the shift.

Behold, the rocket that was a bird that was a dart is again a dart.

Lead, found naturally in water and soil, is also a significant ingredient in bullets and toys produced before 1985.

For the shooter and his friends and the girl it is like the dart never left. The perilous journey continues. Disappearance and return go unnoticed in the course of time between release and strike. Seventeen. Triple green. Two remaining darts follow, neither repeating the same trajectory. The shooter cannot perceive the coldness of space, the heat of fresh blood on a whisker, the lost potential as the woman leaves. She vanishes, like the dart, like she did one day beneath the branches of a large poplar.