The title, "Orison," is an old word for a prayer, and that shapes how the three lines read. The speaker is addressing the morning directly, the way someone might speak to a friend or a higher power, and asking it for help: "put me in order." It is a small, quiet request, but it suggests the speaker feels scattered or unsettled and hopes the day's beginning can set things right.
The comparisons are what make the poem interesting. Order is likened to "the afternoon" and to "a letter home." Afternoon feels settled, with the day already underway and things in their place. A letter home is more tender: it means gathering your thoughts and telling them plainly to someone who matters. Together they suggest an order that is calm and warm rather than strict. The mood is hushed and humble, a little vulnerable, and the brevity of the poem makes the plea feel sincere. It reads like a whispered wish, not a demand.