The action-reaction of light

Light flows from brightness to darkness.

Brightness turns into darkness, and darkness turns into brightness.

Just like:

Energy turns into matter, and matter turns into energy.

Time turns into distance, and distance turns into time.

Solid turns into fluid, and fluid turns into solid.

But:

Light can never flow from darkness to brightness.

Just like:

Energy never flows from cold to hot.

Matter never flows from empty to full.

Time never flows from the past back to the future.

Now,

There are only ever two points in space that light travels between at
any one time:

Start + destination.

We can call the 'start' point, point A.

We can call the 'destination' point, point B.

Point A is therefore bright.

Point B is therefore dark.

Light flows from point A to point B.

Brightness turns into darkness, and darkness turns into brightness.

Point A turns into point B, and point B turns into point A.

Destination turns into the start, and the start turns into the
destination.

-Josh.