This is perhaps one of Hardy's most well-known poems. It describes the speaker of the poem looking out across a barren, wooden landscape on one cold evening in winter. The sudden hopeful song of an aged thrush, however, causes him to question his pessimistic mood and the hope that he is not aware of.
The lines you have selected are part of the second stanza which paints a series of funereal images describing the landscape that the poet contemplates:
The land's sharp features seemed to be
The Century's corpse outleant,
His crypt the cloudy canopy,
The wind his death-lament.
The ancient pulse of germ and birth
Was shrunken hard and dry,
And every spirit upon earth
Seemed fervourless as I.
Note how this stanza supports the bleak landscape that the poet contemplates in stanza 1: the words used and images created help us think that the landscape itself is dead and barren, just as the poet's perspective is barren and joyless. Consider the choice of diction of words such as "corpse", "crypt" and "death-lament". The lines you have selected establish and build upon this repression by referring to Nature as "the ancient pulse of germ and birth" - the force that gives and sustains life, but which is now "shrunken hard and dry", thus supporting and sustaining the pessimistic, joyless mood of the poet.
What is key to understanding this presentation of nature is that Hardy shows in this poem that Nature is an arena of bleak struggle and conflict without plan or purpose, but also that paradoxical it is also a site of astonishing creativity.