How is Romanticism defined in "The Mouse’s Petition" by Anna Laetitia Barbauld?

Barbauld's "The Mouse's Petition" reflects Romantic concerns in a number of ways; her poem also exhibits some key traits of Romanticism from the very beginning, given that it opens with a quotation from Virgil, in line with the tendency of Romantic literature to allude to the Classics as a basis for their philosophy. Barbauld wrote this poem and addresses it to her friend Dr. Joseph Priestley. On a surface level, then, it reflects Romantic concerns about the advancement of science leading to the exclusion of humanity and kindness in that it is, on the face of it, a petition against the use of animals in scientific experiments. The speaker in the poem, the mouse who has been caught in a trap, defines itself as "a pensive captive," and prevails upon the doctor not to use its "guiltless blood" as a "tyrant" might. The mouse here can be read as representative of nature and the world's animals and natural world in general, appealing to the doctor's "philosophic mind" as it begs for its life to be viewed as equal to others. In writing the poem in the voice of the mouse, giving it an erudite means of expression, Barbauld serves to emphasize this idea of smaller creatures as being equally capable of internal thought and deserving of compassion.
The final stanza of the poem, however, makes clear that the mouse does not simply represent mice and the other casualties of the natural world in the face of scientific advancement. Earlier, it warns the doctor against crushing "a brother's soul" in the form of what he believes to be "a worm." In the final stanza, the poem discusses "an unseen destruction... which men like mice may share," and appeals to "some kind angel" to "break the hidden snare." Evidently, then, the predicament of the mouse in this poem reflects Romantic concerns not only about animals, but also the wider Romantic preoccupation with justice for the poor and disenfranchised and support for revolutionary thinking that would bring down the "tyrant" in government.
"Nature's commoners," the poem states, should be entitled to "enjoy / The common gifts of heaven" without being crushed under "a strong oppressive force." The trapped mouse's cries for "liberty" reflect the Romantic focus upon freedom and justice, particularly for those who have suffered under the industrialization of society and become a tyrannized class. In this case, the mouse seems to embody the poor, upon whom the "tyrant's chain" of oppression often came down; the poet asks the doctor to recall the teachings of the "philosophic" ancients and alludes to "a never dying flame" that moves through every type of matter unchanged in its suggestion that a tyrannized man might turn out to be a brother.
In later years, Anna Barbauld has been studied in feminist terms, as well. Given that Barbauld had a strong interest in scientific endeavors and had long wanted to take part in a world from which she was largely excluded, it could also be argued that the mouse in this poem equally represents the oppressed class of women in society during the Enlightenment.