What are the two things that …

The crow and hemlock tree represent sorrow and depression felt by the poet in this materialistic world. 

Explanation:

Dust of Snow is one of the greatest poems of Robert Frost.This poem gives a very positive message to all of us.As the poem tells about how a little thing can change your mood.

As poet was very sad and stand under a hemlock tree (poisonous tree) and there was a crow,both the tree and crow shows sadness because both are symbolising the sadness and cruelness.

But when the crow shook down some snow from tree on the poet's head then poet felt happy and its changed his mood as well as he saved the remaining time of the day.

So the message conveyed from the poem is that 'a small thing has power to change your mood whether it doesn't matter for you'.

Robert Frost uses the elements of the fearsome crow and poisonous Hemlock tree to do something good – shake the white, pure snow off the branches. This good act lifts the suicidal person’s spirits causing him to change his mind about killing himself. The small act causes the man to have an enlightened insight.