The main themes of this poem are nostalgia, childlike hope, a longing for simpler times, and a contrast between light and gloom. Hardy wrote this poem during a time of war and the longing for a childlike peace is present throughout his atheistic narrative.
In the opening lines, a scene of Christmas Eve is described. An old man, perhaps the grandfather, recites a well-known story to a “flock” of children as they sit by the fireplace. During this story, the narrator imagines what the old man is reading and pictures animals in straw kneeling before a baby.
In the third stanza the narrator pessimistically acknowledges that few people would believe the tale in the present time, a time of war. However, the narrator adds that if someone on Christmas Eve were to invite him to ‘see the oxen kneel’ in the barn ‘over yonder’ from his childhood, he would go with the childlike hope that the oxen would really be kneeling beside a baby.
Although Hardy does not believe in the existence of God, there is an obvious parallel to the baby beside the oxen in the poem and the Christ-child. In this case, his desire to have simple faith in a child’s story could be a metaphor for “foolishly” hoping in the existence of God.
There are a few mechanical things in the poem that are worth mentioning. In the third stanza, there is an alliteration of the ‘f’ sound within the first line, “fair a fancy few…weave”. In the last stanza, there are some examples of archaic diction- “barton; yonder coomb” that refer to a time when those words were common, purposefully bringing attention back to the narrator’s childhood. There is a break between the first two and last two stanzas and a “darkening” of the mood. In the first stanza, there is a picture of children sitting by a fireplace, surrounded by light. Yet in the last stanza, which is present day and no longer in “bright” childhood, words such as ‘lonely’ and ‘gloom’ are used. This gradual darkening throughout the poem suggests that Hardy is pessimistic about his present day.
Have you read the poem? https://www.poetryfoundation.org/poems/53215/the-oxen-56d232503c32d