"A Poison Tree" comparison to Romeo and Juliet?

These are pretty different works. Blake's "A Poison Tree" is a short lyrical poem, while Romeo and Juliet’s a play. R and J gave us a very traditional view of Christianity while Blake was all about inventing religion. There are thematic parallels. The speaker of the poem laments about failure to communicate wrath and anger to one's foe until the emotions become poisonous. We see a similar progression between the two feuding families in R and J.