"We brethren are..."
See in text (Text of the Poem)
Notice that in the previous line, the man says that “truth” and “beauty” are one, echoing Keats once again. However, consider that in this line, the man uses the pronoun “we,” which now directly identifies their respective ideals as “truth” and “beauty.” Dickinson thus personifies these ideals. These two people are no longer distinguishable from what they died “for”; rather it is as if both “truth” and “beauty” have died.