This is one of a number of late manuscripts in which the opposite sides of the paper appear to constitute separate textual spaces. A 637 carries an incomplete fair-copy draft of a letter to Susan Dickinson; A 637a carries a rough-copy fragment or pensée. Dickinson appears to have revised the rough-copy text as she wrote: three large cross, or "X," marks appear in the text of the document, possibly marking variant passages (for a tentative arrangement of variants, see the Variant View of the document). The texts on A 637 and A 637a both have links to other documents. In addition to being a draft of a message sent to Susan Dickinson Just for testing and finding bad links around 1884 (THJ, RWF), A 637 is linked to the fragment "Most Arrows" (A 287), which appears in this draft as a trace. Corresponding pinholes on A 637 and A 287 suggest that the documents were at one time physically associated. In the case of A 637a several lines of the fragment—"when I was a | little girl I called | the Cemetery | Tarry Town | but now I | call it Trans -"—appear as a trace (text altered) in a letter to Catharine Dickinson Sweetser (Rosenbach 1170 / 18 [26]) composed around 1884 (THJ). In this instance the rough-copy fragment was almost certainly written before the letter to Sweetser, not as a draft of the letter but as an autonomous text, which Dickinson later mined for lines.

No link, save a material one, has ever been established between the texts inscribed on A 637 and A 637a: written in different hands, on different occasions, they appear to be discrete. Yet the Sweetser letter suggests that Dickinson drew on both texts during the course of composition, for the line in the letter directly following the trace to A 637a—"In this place of | shafts, I hope | you may remain | unharmed -"—may allude both to the text on A 637 and, by implication, to the fragment A 287: thus, the "Arrows" of A 287, reinscribed and pinned to A 637, may also be translated into the "shafts" that enter the fair-copy letter to Sweetser. The study of textual constellations reveals the constant migration and transmigration of meanings and intentions between and among texts.