The poem is written with an awareness of how it appears on the printed page, in particular in relation to the line breaks. For example, the first line contains only one word, "If." The rest of the phrase, "you came back," follows on line 2. There is no grammatical reason for splitting up the phrase in this manner. The same device is used to begin the fifth stanza. The effect is to place much greater emphasis on that one word "if" then would otherwise be the case and makes it clear that the desire of the speaker is to be taken more as fantasy than realistic hope. The arrangement of the line is also a cue for the reader, when reading the poem aloud, as to where to place emphasis and pauses.