Which two sets of lines in this excerpt from Thomas Hardy's "The Darkling Thrush" signify hope in the midst of despair?

1) And Winter's dregs made desolate
The weakening eye of day.
The tangled bine-stems scored the sky

2) And all mankind that haunted nigh
Had sought their household fires.

3) The ancient pulse of germ and birth
Was shrunken hard and dry,

4) At once a voice arose among
The bleak twigs overhead
In a full-hearted evensong

5) An aged thrust, frail, gaunt, and small,
In blast-beruffled plume,

6) Had chosen thus to fling his soul
Upon the growing gloom.