Final answer:
William Blake's poems are characterized by prophetic visions that reflect the Romantic movement's themes of idealizing nature, freedom, and spirituality. His work often tackled social issues through symbolic language imbued with Romantic ideals.
Step-by-step explanation:
William Blake's poems often tried to envision the future through prophetic visions. Blake's work is characterized by its visionary nature and the way it addresses social issues indirectly through metaphor and symbolism, as seen in his reference to the 'charter'd streets' and 'charter'd Thames' to comment on societal constraints.
His poetic style aligns with the Romantic movement, which glorified nature, common people, exotic places, and the historical past, and was opposed to the rationalism of the Enlightenment.
The Romantic movement (a. romanticism) is answered in the referenced question and is an essential context for understanding Blake's work.
His poems embody this movement's values by often presenting idealized visions of humanity and a yearning for freedom from societal restraints, which has been linked to the broader themes of nature and spirituality that are common in the Romantic literature.