I dream'd there would be Spring no more, That Nature's ancient power was lost: The streets were black with smoke and frost, They chatter'd trifles at the door:
I wander'd from the noisy town, I found a wood with thorny boughs: I took the thorns to bind my brows, I wore them like a civic crown:
I met with scoffs, I met with scorns From youth and babe and hoary hairs: They call'd me in the public squares The fool that wears a crown of thorns:
They call'd me fool, they call'd me child: I found an angel of the night; The voice was low, the look was bright; He look'd upon my crown and smiled:
He reach'd the glory of a hand, That seem'd to touch it into leaf: The voice was not the voice of grief, The words were hard to understand.
Now Tennyson's channeling Leslie Knope, because we're apparently getting some of Tennyson's kindergarten dream journal.
This time, he dreams that Nature herself has stopped working and spring doesn't come when it's supposed to.
The speaker wanders through a town where people cruelly make fun of him.
He's wearing a "crown of thorns," you say? Well, who does that sound like? Yep—The Big Guy himself: Jesus.
Here, Tennyson feels persecuted in his dream, like Jesus. It may also link him to Jesus in another way: being a martyr for some cause. He's suffering because he mourns for Arthur's death, and people are making fun of him for it—stupid, mean people.
An angel comes on the scene and smiles at him, and also says something that the speaker can't understand.
It seems like the angel approves of his grief. Maybe the angel is supposed to be Arthur's spirit? At any rate, when the angel touches the crown of thorns on Tennyson's head, it turns "into leaf," another image of renewal and rebirth.