In the quote from Marilynne Robinson's "Housekeeping," the author compares having a close relationship with a sister or friend to being in a well-lit house at night. Those outside can observe, yet the individuals inside are not obliged to engage with them. This metaphor illustrates the comfort and security that strong connections provide, allowing those within their circle to define their boundaries while minimizing outside interference.

The sentiment conveys that true companionship fosters a sense of smugness for those who have it, which is often desirable for lonely individuals. The harmony and safety that come from one solid relationship create a refuge that is enviable to those lacking such bonds. The quote highlights the intrinsic value of human connections and the peace they offer in the face of external scrutiny.