The speaker is defending her inner life from someone who wants in. She admits she keeps a guarded face with almost everyone, revealing herself only to one or two trusted people. In her most private self, she contemplates lilies—an image of something delicate, rare, and set apart. Then she turns on the intruder: why should you, whose roses grow in common ground, profane the cloister I have found? Roses here feel open and ordinary, shared with everyone; lilies belong to a quieter, holier space. The word “cloister” makes her privacy feel almost sacred, not just shyness. The mood is protective and a little wounded, as if someone has pushed too close and forced her to explain a boundary that should have been obvious. Ultimately, it’s about the right to keep part of yourself hidden, even from those who think they mean well.
To an Intruder — Summary
Because I show a guarded face To all the world but one or two, And in my heart's most secret place
Consider lilies, why should you Whose roses grow in common ground Profane the cloister I have found?