"What he inscribed" [sonnet ars poetica]

He hid for long years to consider the page
its face with the blizzardy chaos of snow
he slashed a thin line as the passing carriage
leaves guidance for whither the walker might go
the clomp of a hoof   the trudge of a foot
the slide of a sled   sly slither of a snake
whatever he scrawled   howsoever he put
his mark on a field as he slit through the flake
the composite of flakes   dense cluster of day
white noise white nights   blear blustry silence
white chocolate to take a dark chocolate touche
where black is a blood inkling victim or violence
  he sat for a decade till what he inscribed
  should shatter the swaddle of thought he'd imbibed