In her poem, "Hope is the Thing with Feathers," Dickinson uses the image of a bird to symbolize the importance of hope. Thus, hope has feathers, like a bird, because it can raise you up in difficult times.

In the second stanza, Dickinson describes the tune, or song, produced by the bird, and says that this song is "sweetest - in the Gale." The gale is a reference to the storm mentioned in the next line. The storm symbolizes the difficult times that everybody experiences in their lives, and thus the gale symbolizes perhaps one of those times, or perhaps the feeling of anguish that comes with those times.

Dickinson is saying here that the bird's song is "sweetest," or the most beautiful it can be, during a storm—or during difficult times—because those are precisely the times when one needs most of all to have some hope. Those are the times at which hope is most appreciated.

What is the gale in "Hope Is the Thing with Feathers," and what does hope do in it?

That line from "Hope Is the Thing with Feathers" is found in this context:

And sweetest - in the Gale - is heard -

In this poem, hope is compared to a bird (a "thing with feathers") that can never be quietened, not even in the storms of life. A gale is a very strong wind, much like you would find in a hurricane or a tornado. This is a metaphor for those times in life when trouble seems to toss you around, and you don't even know where you will land when things calm down.

Despite being in the middle of these tumultuous circumstances (the gale), hope never gives up. It keeps "singing" through the stormy winds and perches deep within the speaker's soul so that she is never without it.

In the end, the gale cannot harm the metaphorical bird of hope. Hope will always persevere.