A speaker settles into the end of a day and asks for very little: order, books, an orange, one lamp. The opening makes safety sound a bit sad. Being "safe as a ruin" suggests someone who is protected only because they are already worn down, no longer worth troubling. Even the books, which should comfort, carry "unrest," so the speaker's retreat isn't truly peaceful. Their mind is still busy.
The small, almost monastic details, the single orange and the one light, make the evening feel hushed and self-contained. Then the last stanza shifts the mood. The silence "between us" shows the speaker isn't alone, and that distance has opened up with someone close. Comparing it to a door "to the north" makes it feel cold and slowly widening, something that has grown without anyone deciding it. The poem ends on quiet loneliness, softened by routine but not cured by it.