Deep in the trees, if you knew where to look, was the line. It was where sandy soil became fruity mulch, where slim willows gave way to green giants. It was where the ocean had been, once upon a time nobody could recall, or comprehend.
It was where the animals began to have pockets. One side of the line, zebras have birth to bow-legged infants; the other, bore them safe in a black-and-white pouch until ready to walk. One side, squirrels stored nuts in secret larders; the other, flat against their stomachs.
The line mattered, but no-one yet knew why.