The vastest earthly Day — All Souls' Day

The vastest earthly Day 1
Is shrunken small
By one Defaulting Face
Behind a Pall－
(F.1323/J.1328)
[1] Day:: All Souls' Day, the day to commemorate departed loved ones.
[1, 2] earthly, small:: common, unnoticed; compared with All Saint's Day.
[3] Defaulting Face:: face of the dead, to be remembered.
[4] Pall:: a hint on death.