Provide a summary of "A Night-Rain in Summer" by James Leigh Hunt.

In the first stanza, the speaker seems to be addressing an absent person, which is an example of apostrophe, or perhaps he is addressing himself. Given that he uses a first person narration (using "I") in the second stanza, he does seem to be addressing himself and/or giving himself advice. 

The outside air is refreshing. He wants it to fill the room as it fills the outside world "With the breath of rain's sweet might." He tells himself to listen ("Hark") to the "burthen" of the rain. This "burden" of the rain is meant to be ironic because the rain is actually a cleansing, refreshing notion to him. The burden is just the rain striking the ground and the walls of his room. Note that "Love" is capitalized. With this, the speaker notes either the abstract notion of love or maybe even God. Thus, there is the presence of an abstract love or some spiritual Being that persists in the air and rain providing for peace and "gentle sleeps." The rain has a calming effect on him. 

In the second stanza, the speaker says that he will not have any lights in his room. The darkness is natural and peaceful. The window will be open ("not a window-pane") so that he can fully embrace this cleansing, fresh air and rain. He invokes God with "God's darkness" and this means the night itself. In this spiritual connection with God and nature, the speaker is very much a Romantic. He will rest peacefully because of this spiritual connection. The last line might also suggest the natural rest of death: "In the pure earth-shadow of natural rest." In either sense, the "night-rain" with its natural purity and spiritually calming presence, will bring him a peaceful sleep.