The thought beneath so slight a film — Eye Disorder

Dickinson's thought hidden beneath a film was agitating or calm, as surge or Apennines. To read her poetry in depth, we must remove that film.

Film is a morbid growth upon the eye _{(OED 4)}. This poem describes Dickinson's eye disorder, if she really had one. She stayed in Boston seven months for her eye treatment; however, there exists no medical record. She only wrote "I was sick" in her letters from Boston.

The thought beneath so slight a film－
Is more distinctly seen－
As laces just reveal the surge－
Or mists－the Apennine

(F.203/J.210)

[1] film:: an unhealthy thin layer on the eye, eye disorder.
[2] distinctly seen:: view through a film is peculiar, different as seen with white laces around the subject, or through the mist in a high mountain.
[3] laces:: the surf, white forms on top of waves.
[4] mists the Apennine:: a dimmed view through the mist of the Apennines in Italy.